Contents

How to Manage Pests

Pests in Gardens and Landscapes

Codling Moth

Revised 5 /11

In this Guideline:



  • Identification
  • Life cycle
  • Damage
  • Management
  • About Pest Notes
  • Publication
  • Glossary


Figure 1. Adult codling moth.
Figure 2. Mature codling moth larvae in cut-open cocoons.
Figure 5. Codling moth pupa.
Figure 6. Frass, a mixture of feces and food fragments, fills tunnels that codling moth larvae have bored into this apple.
Figure 7. Codling moth larva in a walnut.

Codling moth, Cydia (Laspeyresia) pomonella, is a serious insect pest of apples, pears, and English walnuts.

IDENTIFICATION

Codling moth adults are about 1/2 to 3/4 inch long with mottled gray wings that they hold tentlike over their bodies (Figure 1). Their appearance blends well with most tree bark, making them difficult to detect. If you are trapping the adults, you can distinguish codling moth from other moths by the dark, coppery brown band at the tip of their wings.

The larvae are white to light pink “worms” with a dark brown head (Figure 2). They are one of the few caterpillars likely to be found inside pear or apple fruit. Navel orangeworms also might be found in walnuts, but these can be distinguished from codling moth larvae by the crescent-shaped markings on the second segment behind the orangeworm head and by the excess webbing they leave in the nut.

LIFE CYCLE

Codling moth overwinters as full-grown larvae within thick, silken cocoons under loose scales of bark and in soil or debris around the base of the tree. The larvae pupate inside their cocoons in early spring and emerge as adult moths mid-March to early April. The moths are active only a few hours before and after sunset, and they mate when sunset temperatures exceed 62°F.

After mating each female deposits 30 to 70 tiny, disc-shaped eggs singly on fruit, nuts, leaves, or spurs. After the eggs hatch, young larvae seek out and bore into fruit or developing nuts. After completing development they leave the fruit and drop from the trees to search out pupation sites and continue the life cycle in the soil or on debris under the tree; some crawl back up the tree to pupate in bark crevices (Figure 5).

The rate of development will vary with temperature, proceeding more rapidly in warmer weather and climates. Depending on the climate, codling moth can have two, three, and sometimes four generations per year.

DAMAGE

On apples and pears, larvae penetrate into the fruit and tunnel to the core, leaving holes in the fruit that are filled with reddish-brown, crumbly droppings called frass (Figure 6). If left uncontrolled, larvae can cause substantial damage, often infesting 20 to 90% of the fruit, depending on the variety and location. Late maturing varieties are more likely to suffer severe damage than early varieties.

In walnuts, larvae feed on the kernels (Figure 7). Nuts damaged early in the season when the nuts are quite small will drop off trees soon after damage occurs. Nuts damaged later in the season will remain on trees, but their kernels are inedible. Walnuts aren’t as favored a host as apples and pears, and untreated trees might incur very little to modest damage (10 to 15% of the nuts), depending on the variety and location.

MANAGEMENT

Codling moth can be very difficult to manage, especially if the population has been allowed to build up over a season or two. It is much easier to keep moth numbers low from the start than to suppress a well-established population. In trees with low levels, codling moth often can be kept to tolerable levels by using a combination of nonchemical management methods; however, it is important to begin implementing these measures early in the season.

Where populations are moderate to high and many infested trees are nearby, insecticide applications might be necessary to bring populations down to low levels. To be effective, the timing of insecticide spray applications is critical, and several applications are necessary, especially with newer, less toxic pesticides. In most backyard situations, the best course of action might be to combine a variety of the nonchemical and/or low toxicity chemical methods discussed below and accept the presence of some wormy fruit. If eating wormy fruit, be sure to cut out damaged portions, because they might contain toxins (aflatoxin) generated by mold. It is ideal to make codling moth management a neighborhood project, because your trees can be infested by moths from your neighbor’s trees, despite your own best efforts at keeping populations of this pest down.

Nonchemical Control

Several methods are available for reducing codling moth that don’t require using insecticides. Selecting varieties that are less susceptible to damage, such as early-maturing apples and pears and late-leafing walnuts, can greatly reduce the potential for damage. This can be especially important in the hot Central Valley climates that have additional generations and result in higher population pressure.

Once trees are planted, nonchemical control methods include sanitation and fruit bagging. These methods are described below. Thinning out and removing infested fruit on the tree is an especially important part of an IPM program for codling moth. Pruning trees to a height where the canopy is easy to reach also will facilitate management of this pest.

If a backyard tree or orchard has a very high moth population, it might be impossible to satisfactorily reduce codling moth without using pesticides. Also, nearby orchards or backyard trees in which no control program is in place can serve as a continual source of codling moth and can make it even more difficult to limit damage through nonchemical means alone.

Sanitation. Sanitation should be the first step in any codling moth control program, and it is even more important for those wishing to use primarily nonchemical management approaches. Every week or two, beginning about six to eight weeks after bloom, check fruit on trees for signs of damage. Remove and destroy any infested fruit showing the frass-filled holes. Removing infested fruit before the larvae are old enough to crawl out and begin the next generation can be a very effective method for reducing the population. Thinning out the infested fruit has the added benefit of encouraging the remaining fruit on the tree to grow larger. It also might improve spray coverage, if sprays are used.

It also is important to clean up dropped fruit as soon as possible after they fall, because dropped fruit can have larvae in them. Removing infested fruit from the tree and promptly picking up dropped fruit from the ground is most critical in May and June but should continue throughout the season.

Bagging fruit. Excellent control can be achieved by enclosing young fruit in bags right on the tree to protect them from the codling moth. This is the only nonchemical control method that is effective enough to be used alone and in higher population situations. However, it is quite time consuming to apply the bags, so this method is most manageable on smaller trees with fewer fruit. You can bag all the fruit on the tree or just as many fruit as you think you will need. Keep in mind that unbagged fruit are likely to serve as a host and increase the pest population, so it would be prudent to employ sanitation to keep the population in check.

Bagging should be done about four to six weeks after bloom when the fruit is from 1/2 to 1 inch in diameter. Prepare No. 2 paper bags (the standard lunch bag size that measures 7 1/4 inches by 4 inches) by cutting a 2-inch slit in the bottom fold of each bag. Thin the fruit to one per cluster. Slip the thinned fruit through the 2-inch slit so that it forms a seal around the stem and staple the open end shut.

It is difficult or impossible to bag certain varieties with very short stems such as Gravenstein. Also late-developing varieties might be attacked by codling moth even before they are 1/2 inch in diameter, so they might not be protected. Some gardeners have found success with cotton tie string bags; nylon bags, however, aren’t effective.

This technique won’t affect the maturity or quality of the fruit, but it will prevent full color development on red varieties. You’ll need to open some bags to check for ripeness as harvest time approaches. Some people open the bags up a week or two before harvest to allow color development, but the fruit still might be attacked if codling moth eggs are being laid. Other benefits to bagging include protection from sunburn and larger fruit as a result of diligent thinning.

Trapping. Hanging traps in each susceptible fruit or nut tree might help to reduce codling moth populations on isolated trees but isn’t a reliable way to reduce damage. If it works at all, this method likely will have the most effect where trees are isolated from other trees harboring codling moth (e.g., apple, pear, or English walnut) and when several traps are placed in a tree. Use in combination with sanitation and other control methods for the best effect and expect damaged fruit.

Codling moth pheromone traps are important for monitoring flight activity of moths to help time insecticide treatments. Traps are available from many commercial sources, such as hardware stores, garden centers, or online. These traps usually have a sticky cardboard bottom and are baited with a pheromone (sex attractant) lure. The lure mimics the scent of a female moth, attracting males to the trap. Traps should be put up in mid-March in the Central Valley and by the end of March in coastal areas. They should be hung as high as possible in the tree canopy. Check them every few days for moths. Only one trap is required if you are using them to monitor moth flights to time insecticide treatments. See the Insecticides section for more information.

Trunk banding. A traditional, nonchemical method for controlling codling moth is to trap mature larvae in a cardboard band as they climb the trunk seeking a place to pupate. Banding works best on smooth-barked varieties such as Red Delicious apple, which don’t provide good alternative pupation sites. Scaly-barked varieties such as Newtown Pippin and most types of pears have so many crevices on the trunk that many larva will pupate before they get to the banded area. However, even in the best situations, banding will control only a very small percentage of the codling moth, because many pupate elsewhere on the tree or in the ground. Additionally, if bands aren’t removed and destroyed in a timely fashion, they could increase the population, so banding no longer is recommended for control in home gardens.

Biological control. Although a few predators such as spiders or carabid beetles might feed on codling moth larvae or pupae, naturally occurring biological control isn’t effective. In commercial walnut and pear orchards, releases of the tiny wasp Trichogramma platneri have been used successfully to manage codling moth in combination with mating disruption or soft pesticides. This method hasn’t been successful in commercial apples and hasn’t been tested in backyards.

Insecticides
Tools: Degree-day calculator, Sunset temperatures, Degree-day table

Proper timing of insecticide sprays is critical if they are to be effective against codling moth; they should be applied before or just as eggs are hatching. Once the worm has gone into the fruit or nut, it is protected from pesticides.

Timing with degree-day calculations. The most effective way to time insecticide sprays is with a pheromone trap and a degree-day calculation. This is what commercial growers use. The trap lets them know when each generation or flight begins. The degree-day calculation lets them know just when egg hatch will occur and when the next generation should begin to fly. You can calculate degree-days with a maximum-minimum thermometer and a degree-day chart, or you can use the automated weather stations and degree-day calculator on the UC IPM Web site.

Timing by monitoring stings. Although timing sprays is best done with the use of degree-day calculations, home gardeners can also monitor fruit in their trees to detect the beginning of egg hatch. Starting three to four weeks after bloom, check fruit at least twice a week looking for the first “stings,” or tiny mounds of reddish-brown frass about 1/16 inch in diameter. If you scrape the frass away you will see the tiny entry hole where the newly hatched larvae has just entered the fruit. Be sure to examine the fruit where it touches another fruit, as this is a common place to find an entry hole. Spray the tree as soon as you see the first sting; however, first remove any fruit with stings from the tree, as the insecticide won’t kill any larva that already have entered the fruit. Expect to have more damage with this monitoring method than the degree-day method, since it can be difficult to find the very first sting.

Home orchards might be able to achieve an acceptable level of control by spraying the first spring generation and using nonchemical methods to maintain a low population for the rest of the season. However, if heavy infestations have occurred in previous years, if there are unmanaged host trees nearby, or if tolerance for damage is very low, the summer generation(s) also need to be treated.

In cooler coastal areas look for the first stings from the spring generation in early to mid-May, about a month after bloom. Look for new stings from the single summer generation beginning in mid-July to mid-August, about 10 to 13 weeks after the spring hatch begins. Coastal areas usually have just two generations per year.

In the warmer Central Valley area look for the spring generation stings in mid- to late April, about a month after bloom. Look for new stings from the first summer generation beginning in early to late June, about eight weeks after the spring hatch began. In the Sacramento and Northern San Joaquin valleys, a second and last summer generation will begin in early to mid-August. In the very hot southern San Joaquin Valley, look for the second summer generation stings to begin in mid-July and the third summer generation to begin in mid-August.

Codling moth granulosis virus. Recently a new biological insecticide, CYD-X, a granulosis virus that affects only larvae (caterpillars) of the codling moth, has become available to home gardeners in California. Codling moth larvae must ingest this virus for it to be effective. Once ingested, the virus infects the digestive tract of the caterpillar causing a disease that kills it within three to seven days. It doesn’t affect other insects, humans, pets, or wildlife and is OMRI listed as suitable for use in certified organic production. University of California trials have shown that this product, when applied weekly during egg hatch throughout the season, is as effective as carbaryl sprays at controlling codling moth in backyard trees. More applications are needed—carbaryl must be applied only every 14 to 21 days or one to two times per generation—but many environmentally conscious gardeners are willing to make this trade off. CYD-X also has the advantage of having no preharvest interval, so applications can be made up until the time of harvest and there are no limits on the number of times you can spray it.

Like other insecticides, granulosis virus should be applied as soon as the eggs of the first generation codling moth hatch. If you are using pheromone traps and degree day calculations as described above, this would be 200 to 250 degree-days after you begin regularly catching male moths. If you are just checking fruit, this would be when you see the first stings. Make applications weekly after that. You’ll need a good sprayer, and you must get good coverage of fruit. Adding 1% oil to the application can improve effectiveness. CYD-X is a new product that might be difficult to find in stores but can be ordered on the Internet.

Spinosad. Spinosad is a biological product made from a naturally occurring bacterium called Saccharopolyspora spinosa. It is a lower-toxicity material that is safe for most beneficial insects as well as for people, pets, and the environment although it is more toxic to beneficials than granulosis virus. Repeated applications each generation are necessary for acceptable control. The first spring generation requires three sprays applied at 10-day intervals beginning at egg hatch (i.e., 250 degree-days, or when the first stings are found). For any subsequent summer generations, two sprays should suffice with the first spray applied at the beginning of each new egg hatch and the second spray applied 10 to 14 days later. No more than six sprays should be applied per season, and they shouldn’t be applied within seven days of harvest. The addition of a 1% horticultural oil to the spray tank will further enhance the effectiveness of this material. Spinosad is available through retail outlets under various trade names including Monterey Garden Insect Spray or Green Light Spinosad Lawn & Garden Spray.

Carbaryl. One of the more effective materials against codling moth is the broad-spectrum insecticide carbaryl (Sevin). However, this material has significant drawbacks. It remains effective for 14 to 21 days, but it is very disruptive to natural enemies and honey bees. Applying more than one carbaryl spray per season might lead to an outbreak of pest mites. Also carbaryl has been associated with water quality problems. If your tree is heavily infested and more than one spray is needed, it might be prudent to alternate this material with granulosis virus or spinosad. Carbaryl never should be sprayed during bloom or when bees are present. It also shouldn’t be used on apples within one month of bloom, as it can cause the fruit to drop; use one of the other materials if a spray needs to be applied at this time. The homeowner shouldn’t apply carbaryl within three days of fruit harvest or 14 days before walnut harvest.

Carbaryl should be applied at 250 degree-days or as soon as you see the first sting in spring. A second application might be needed at 650 degree-days, or 21 to 28 days later, to cover the prolonged spring emergence. If later summer generations require treatment, a single carbaryl application should suffice for each subsequent generation, as the insect develops more quickly during the warm weather of summer. Refer to the online degree-day guidelines for timing these later sprays or visually monitor for each new generation using the timing guidelines above.

Other materials. Bacillus thuringiensis, pyrethrum, and pyrethrin/rotenone combinations are low toxicity materials that have been tested and haven’t been found to be effective at controlling codling moth. Horticultural oil has shown variable efficacy when used alone but can be mixed with granulosis virus or spinosad to improve performance. Mating disruption products that employ large quantities of pheromone to prevent mating or pheromone plus an insecticide to attract and kill male moths have proven effective for large commercial plantings but aren’t effective on small orchards of fewer than 5 acres. In fact, mating disruption can increase damage if used on small plantings or individual trees.

WARNING ON THE USE OF PESTICIDES

Ohlendorf, B. 1999. Integrated Pest Management for Apples & Pears, 2nd ed. Oakland: Univ. Calif. Agric. Nat. Res. Publ. 3340.

PUBLICATION INFORMATION

Pest Notes: Codling Moth
UC ANR Publication 7412

Authors: J. L. Caprile, UC Cooperative Extension, Contra Costa Co.; and P. M. Vossen, UC Cooperative Extension, Sonoma/Marin Co.

Produced by UC Statewide IPM Program, University of California, Davis, CA 95616

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Top of page

Found in all apple-growing areas of the world, the codling moth (Cydia pomonella) is considered to be one of the most destructive pests of apples. Adults are gray to brown moths with a 3/4 inch wingspan. They have a chocolate-colored patch at the tip of each forewing and coppery transverse markings.

Codling moth larvae are pink or creamy white caterpillars with mottled brown heads that tunnel through apples directly to the core. As they feed, they push out mounds of fecal material, called frass, which gathers around the entrance hole. Damage lowers the market value of the fruit and makes it unfit for human consumption. Alternate host plants include pears, crabapples, walnuts and stone fruits.

Note: The codling moth was introduced to North America by the colonists more than 200 years ago and is now one of the leading pests in home orchards.

Life Cycle

Full grown larvae pass through the winter in a cocoon beneath loose bark or in orchard litter. Pupation takes place in the spring. Moths begin emerging about the time that apple trees are in bloom and lay an average of 50 to 60 eggs on leaves, twigs and fruits. Once eggs hatch the larvae feed briefly on leaves, then damage fruit by boring into the centers. Larvae feed for three weeks, then leave to seek a suitable place to spin cocoons. There are two generations per year.

How to Control

  1. Scrape loose bark in early spring to remove overwintering cocoons and then spray All Seasons® horticultural oil to eradicate eggs and first generation early instar stages.
  2. Beneficial nematodes are microscopic, worm-like parasites that actively hunt, penetrate and destroy immature stages of this pest. Spray on trunks and main branches, and also over the soil out to the drip line for a 60% to 90% mortality in pre-pupae.
  3. Use pheromone traps to determine the peak flight period for moths, then release trichogramma wasps to attack eggs. Pheromone traps will also help reduce male moths where populations are low and trees are isolated.
  4. Bt-kurstaki (Bt) and Spinosad sprays are moderately effective since the larvae spend so little time feeding outside the fruit. Apply during egg hatching only (consult with a local extension agent for exact times).
  5. Surround WP — a wettable kaolin clay — can be used to deter a broad range of fruit tree pests (and diseases), and will reduce codling moth damage by 50-60%. Apply before moths arrive and continue for 6-8 weekly applications, or until the infestation is over.
  6. In areas of severe infestation, spray plant-derived insecticides when 75% of petals have fallen, followed by three sprays at 1-2 week intervals. These natural pesticides have fewer harmful side effects than synthetic chemicals and break down more quickly in the environment.

Tip: In spring, band tree trunks tightly with corrugated cardboard strips (4- to 6-inches wide) to provide a site for larvae to spin their cocoons. Remove and destroy the strips after cocoons are formed.

Apple-Codling moth

Cydia pomonella

Pest description and crop damage This is the most serious pest of apples in the PNW, especially in warmer, dryer areas. Adult moths are 0.5 inch wide, with alternating gray and white bands on the wings and a copper band on the wing tips. Larvae are whitish with a black head when immature, and pinkish with brown heads when mature. Larvae are 0.1 inch long at hatch and 0.8 inch long at maturity. Pupae are brown and about 0.75 inch long. The eggs are very tiny and rarely seen.

Larvae feed directly on the fruit, boring into it and feeding within. Stings are shallow depressions where feeding occurred and stopped. Larvae bore into the fruit, leaving a characteristic tunnel filled with frass that extrudes from the hole on the fruit surface. Entry holes may be anywhere on the fruit.

Biology and life history Codling moth overwinters as mature larvae in silken cocoons (hybernaculi) spun under loose bark, in the soil, or in litter at the base of the tree. Pupation takes place in the spring around the time the first blossoms are showing pink, and adults emerge around bloom. Adults are active only at dusk and dawn and lay eggs on leaves, or occasionally on fruit.

The larvae emerge, begin feeding on fruit, and may bore to the center of developing fruit to feed on the flesh and seeds. As they mature, they push frass out of the entry hole. After 3 to 4 weeks, the larvae leave the fruit to seek a sheltered spot on the tree to spin cocoons.

The larvae may overwinter in the cocoon, or they may emerge in 2 to 3 weeks as a new flight of adults. These adults are active in July and August. In warm areas, there may even be a third generation. Larvae of this brood often penetrate fruit but do not complete development before harvest or the onset of winter.

Sampling and thresholds The development of codling moth can be predicted by the accumulation of heat units, or degree-days using phenology models. By knowing the stage of the insect, we can target management to specific life stages that are susceptible. For codling moth, that means that our treatments are targeting the eggs or the wandering larvae during the brief period between egg hatch and the time when the larva is able to penetrate the fruit where it is protected. Phenology model recommendations can originate with your local Extension resource, crop consultant, software system, or use of an online degree-day calculator. It is important to make sure that you are using an appropriate tool/model for your region. Homeowners can also benefit from use of degree-day models to predict management timing.

To calculate biofix for degree-day modeling hang traps with 1 mg pheromone lures in the upper canopy at pink. Biofix is the first capture of multiple male moths in a trap or consistent capture of multiple males over more than one trap. The biofix date is used as the point to start accumulating degree-days for the Stanley and Hoyt (1987) degree-day model, which is still the best model for PNW locations south of 46°N. North of this latitude, the no-biofix model can be used (Jones et al. 2008). The CM-DA lure contains a food odor and will catch females as well as males. Capture of females indicates potential for eggs and damage but models use male captures for setting biofix.

When mating disruption is used, monitor the orchard with pheromone traps baited with 1 mg pheromone or CM-DA lures set in the upper third of the canopy. If more than five male moths are captured in a trap over the first generation, check the orchard for fruit damage or apply a conventional insecticide. If fruit damage exceeds 0.5% at the end of the first generation, use conventional insecticides to provide supplemental control against the second generation. If more than two male moths are captured in a trap during the second generation, a conventional insecticide may be necessary.

Management-cultural control

In small orchards, sanitation by removing and disposing of young damaged fruit can be helpful in reducing codling moth. Check regularly throughout the season for fruit with frass-filled holes. Removing and destroying infected fruit prior to larvae emergence preceeding pupation can help reduce overall populations. Picking up dropped fruit from the ground likewise can be an effective sanitation measure. Homeowners can bag individual fruit (clusters thinned to one fruit) in paper bags approximately six weeks after bloom, however this can be labor-intensive and more challenging for cultivars with short stems. Fruit will mature completely within bags, however color development on red varieties may be affected. Homeowners can also place corrugated bands of cardboard around the lower trunk to attract larvae looking for a place to pupate. Place in May and remove before the adults begin to emerge in mid-June. The same technique can be used with the subsequent generation(s) later in summer.

Management-chemical control: HOME USE

After petal fall spray and spring and summer sprays

Apply first cover spray at 250 degree-days after biofix, or about 10 days after full petal fall (all petals are off) or 17 to 21 days after full bloom. Insecticides must be timed to target newly hatched larvae before they bore into the fruit. Multiple sprays are often necessary with applications up to every 10-14 days, however sprays can be reduced by monitoring for adult moths with monitoring traps or use of degree-day models (see description above) to properly time insecticide applications to the hatching larvae during the growing season.

  • acetamiprid
  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • carbaryl
  • esfenvalerate
  • gamma-cyhalothrin
  • insecticidal soap-Some formulations OMRI-listed for organic use.
  • kaolin-Applied as a spray to leaves, stems, and fruit, it acts as a repellant to pests.
  • lambda-cyhalothrin
  • malathion
  • mating disruption pheromones-See biorational control above. Not effective for orchards less than 10 acres.
  • permethrin
  • pyrethrins (often as a mix with other ingredients)
  • spinosad
  • zeta-cypermethrin

Management-biorational control: COMMERCIAL USE ONLY

Stages 5-6: Pink application

Mating disruption. Pheromone release devices placed in the orchard interfere with the communication from female to male codling moth and this prevents or delays mating of moths, reducing the number of eggs laid and crop damage. A number of hand-applied pheromone dispensers are available including Isomate C+, Isomate CTT, NoMate, CheckMate, Cidetrak CM, and Checkmate CM-XL 1000. These dispensers are typically applied to trees at densities of 200 to 400 per acre, sometimes with a higher density of dispensers applied to orchard borders. Aerosol devices (also called puffers) for releasing pheromones are increasingly favored for their efficacy and ease of application at densities such as 1 device/a. Substantial fruit damage could result from improper use of mating disruption, therefore follow the label recommendations. Blocks placed under mating disruption should be large, ideally greater than 10 acres, and prospects for success increase when neighboring orchards are also using the tactic and the codling moth pressure is low. Pheromone dispensers can be applied to dormant trees and must be in place before first moth flight around the time of full bloom of Red Delicious. Place within 2 ft of the top of the canopy. If the orchard has a history of codling moth problems, use one or more insecticide applications against the first generation. If a codling moth source exists nearby, use border sprays (five to six rows) of insecticides.

Management-biological (microbial) control: COMMERCIAL USE ONLY

  • codling moth granulosis virus (Carpovirusine, Cyd-X, Virosoft CP4)-Check label for rates. REI/PHI 12 hr. Granulosis virus is a selective biological insecticide that must be ingested to be effective. Thorough coverage is important. The virus degrades when exposed to UV light. If a grower relies only on granulosis virus for codling moth control, frequent applications are necessary (every 7 to 10 days), especially when codling moth pressure is high. The virus controls larvae, but some fruit damage, primarily stings, may be evident. OMRI-listed for organic use.

Management-chemical control: COMMERCIAL USE

After petal fall spray

Apply first cover spray at 250 degree-days after biofix, or earlier for ovicidal materials. This roughly corresponds to about 10 days after full petal fall (all petals are off) or 17 to 21 days after full bloom for ‘Red Delicious’. A second treatment is recommended approximately 14 days after the first (depending on residual) to cover the full period of moth egg laying in the first generation. The first summer generation spray should be applied at 1250 degree-days after biofix, and again a second treatment in 14 days will help cover the entire egg hatch period. Materials with rapid breakdown such as codling moth granulosis virus should be applied on a more frequent schedule.

  • chlorantraniliprole (Altacor) at 3.0 to 4.5 oz/a in no less than 100 gal water per application. Do not apply more than 9 oz/a per growing season. Do not use an adjuvant within 60 days of harvest. REI 4 hr. PHI 5 days.
  • methoxyfenozide (Intrepid 2F) at 16 fl oz/a in up 100 gal water per application. For use against low- to moderate-pressure situations, with alternate control measures such as mating disruption. Use adjuvant; see label. Do not exceed 64 oz/a per growing season. REI 4 hr. PHI 14 days.
  • novaluron (Rimon 0.83EC) at 30 to 50 fl oz/a in up to 100 gal water per application with a second application 14 to 17 days later. Do not apply more than 150 fl oz per growing season. REI 12 hr. PHI 14 days.
  • pyriproxyfen (Esteem 35WP) at 4 to 5 oz/a in up to 100 gal water per application. Do not exceed two applications per season. Do not apply earlier than 14 days after last Esteem 35 WP treatment. REI 12 hr. PHI 45 days.

Spring and summer

  • acetamiprid (Assail 70WP) at 1.7 to 3.4 oz/a in up to 100 gal water per application. Do not make more than 4 applications per year or exceed 13.5 oz/a per growing season. Adding a low rate of horticultural mineral oil improves effectiveness against codling moth. REI 12 hr. PHI 7 days.
  • Chromobacterium subtsugae (Grandevo) at 1 to 3 lb/a. Under heavy pest populations, apply a knockdown insecticide prior to or in a tank mix, use the higher label rates, shorten the spray interval, and/or increase the spray volume to improve coverage. REI/PHI 12 hr. OMRI-listed for organic use.
  • clothianidin (Belay 50WDG) at 3.2 to 6.4 oz/a. For control of first generation codling moth in areas with light pressure and suppression of first generation codling moth in areas of heavy infestation. Do not apply more than 6.4 oz of Belay per acre per season. REI 12 hr. PHI 7 days. Do not feed or allow livestock to graze on cover crops from treated orchards. Belay must not be applied during bloom or if bees are actively foraging. .
  • chlorantraniliprole (Altacor) at 3.0 to 4.5 oz product/a in no less than 100 gal water per application. Do not apply more than 9 oz per acre per growing season. Do not use an adjuvant within 60 days of harvest. REI 4 hr. PHI 5 days.
  • emamectin benzoate (Proclaim 5SG) at 3.2 to 4.8 oz/a in up to 100 gal water per application. For use in low to moderate pressure situations with alternate control measures such as mating disruption. Do not exceed 14.4 oz/a per season. REI 12 hr. PHI 14 days.
  • fenpropathrin (Danitol 2.4 EC) at 16 to 21.3 fl oz/a in up to 100 gal water per application. Will also reduce mite populations but may cause resurgence the same season. Do not exceed 42.7 fl oz per acre per season. REI 24 hr. PHI 14 days.
  • flubendiamide (Belt SC) at 5.0 fl oz/a in a minimum of 100 gal water per application. Do not exceed three applications per growing season. REI 12 hr. PHI 14 days.
  • granulovirus virus M (CpV-M) (Carpovirusine) at 6.8 to 13.5 fl oz/a in 100 gal water per application. Start at the beginning of first generation egg hatch. Apply every 7 to 10 days. REI/PHI 12 hr. OMRI-listed for organic use.
  • indoxacarb (Avaunt) at 5 to 6 oz/a in up to 200 gal water per application. Make no more than 3 applications prior to hand-thinning. No hand thinning after the 4th application. Make no more than 4 applications per growing season. Do not apply more than 24 oz/a per growing season. For use in low- to moderate-pressure situations, with alternate control measures such as mating disruption. REI 12 hr. PHI 14 days.
  • methoxyfenozide (Intrepid 2F) at 16 fl oz/a in up to 100 gal water per application. For use against low- to moderate-pressure situations, with alternate control measures such as mating disruption. Do not exceed 64 oz/a per season. REI 4 hr. PHI 14 days.
  • novaluron (Rimon 0.83EC) at 30 to 50 fl oz/a in up to 100 gal water per application. See label for application timing. Do not exceed 150 fl oz/a per season. REI 12 hr. PHI 14 days.
  • phosmet (Imidan 70W) at 2.1 to 5.7 lb/a in up to 100 gal water per application. REI/PHI 7 days.
  • pyriproxyfen (Esteem 35WP) at 4 to 5 oz/a in up to 100 gal water per application. Do not exceed two applications per growing season. REI 12 hr. PHI 45 days.
  • spinetoram (Delegate WG) at 6 to 7 oz/a in up to 100 gal water per application. Do not exceed four applications per season. REI 4 hr. PHI 7 days.
  • spinosad (Entrust 80WP) at 2 to 3 oz /a in up to 100 gal water per application. Do not exceed 9 oz/a per season. REI 4 hr. PHI 7 days. OMRI-listed for organic use. larvicidal]
  • thiacloprid (Calypso 4F) at 4 to 8 fl oz/a in up to 100 gal water per application. Do not exceed 16 fl oz/a per season. REI 12 hr. PHI 30 days.
  • thiamethoxam/chlorantraniliprole (Voliam Flexi) at 4 to 7 oz/a in up to 100 gal water per application. Do not apply exceed 16 oz/a per season and do not use an adjuvant within 60 days of harvest. REI 12 hr. PHI 35 days.

After the caterpillars get about an inch long in mid-June, they will move down the trunk to hide from predators during the day. You can take advantage of this behavior to trap and reduce the number of larvae on the trees in your yard by making a burlap barrier band trap. To make a band, cut a strip of burlap 12-18 inches wide and long enough to reach around the tree and overlap a few inches. Tie a string around the center of the band and allow the top six inches to flop over to make a two-layered skirt. Tie the band around the tree above the sticky band (if you have one in place). Check the bands every day from early afternoon until about 6 p.m. Gypsy moth caterpillars have hairs that can irritate the skin, so use rubber gloves or forceps to collect all caterpillars from the burlap band. Place the collected caterpillars in a container of soapy water to kill them. If you find any adults or pupae on your trees, you can also kill them by placing them in the container of soapy water. Once the insects are dead, drain off the water and throw the insects in the trash. Take the burlap bands down in August.

At chest height, wrap a 12 – 18 inch tall piece of burlap or light colored cloth around the tree and fasten it with twine around the middle.

Drop the top half of the burlap over the twine and over the bottom half of the burlap to create a “skirt”.

Monitor the burlap bands for caterpillars each day in the late afternoon and sweep any collected caterpillars into a bucket of soapy water.

Watch a brief video about making your own burlap barrier band trap.

Adapted From: “Containing Gypsy Moth”. Andrea Diss. August, 1998. Wisconsin Natural Resources Magazine. Photo Credits: Bill McNee WI DNR.

Almost everyone has bitten into a “wormy” apple or pear, an unpleasant experience. A “worm” in homegrown fruit is not really a worm, but most likely a codling moth caterpillar. Called “one of the most damaging insects of apples and pears,”1 it can be a problem in commercial orchards as well as for backyard fruit trees.

Alternative techniques for dealing with codling moth have been widely accepted by farmers, and have reduced orchard pesticide use by 80 percent according to U.S. Department of Agriculture estimates.2 Successful nonchemical techniques are also available for home gardeners. These include some based on care of trees and fruit, some trapping techniques, a bagging technique, as well as a tiny wasp and a virus that kill these moths. For best results, use a combination of techniques.

Identifying Codling Moths

The codling moth is a gray moth about 3/4 inch across. Usually its wings are marked with copper lines and a gold or bronze spot. Mature caterpillars are white with a brown head and about 3/4 inch long.1

In order to successfully manage codling moths, you’ll need to understand the life cycle of this insect. It spends the winter as a caterpillar in a cocoon, usually under loose bark on a tree trunk or in some other protected spot. Adults emerge from the cocoon in April or May. The females lay eggs on leaves and small fruit for about a month. When the eggs hatch, the young caterpillars feed on the surface of the fruit for a few days, then burrow into the center. They feed about three weeks, then tunnel out of the fruit and find a place to spin a cocoon. In the Northwest, there can be between one and three generations per year.1

Resistant Varieties Can Help

If you’re planting new trees, choose varieties that will minimize future codling moth problems. Early maturing apples, like Jonagolds, Gravensteins, Galas, Macintoshes, and Red Delicious, are less susceptible to codling moth than late-maturing varieties.3Planting trees with semidwarf rootstocks is helpful. The smaller trees will make it easier for you to manage codling moths.3

Thinning Your Apple Crop

Thinning apples so that your tree has only one apple per fruit cluster is generally recommended in order to keep your tree vigorous. (It also allows your tree to produce a good crop every year.) Thin apples when fruit are small (the size of a marble or walnut). When you thin your crop, be sure to remove any fruit that have small holes made by codling moth caterpillars. Bury these apples, or put them in a black plastic bag in the sun for a month. Composting doesn’t destroy all the caterpillars.3

Picking up Dropped Apples

Collect any dropped fruit weekly because caterpillars leave dropped fruit quickly. Dispose of them the same way as thinned apples.3

Trapping Moths

There are three ways to trap codling moths: pheromone traps, black light traps, and homemade traps. Pheromones are attractants produced by female moths to attract males. Pheromone traps release this attractant chemical and also have a sticky surface for trapping moths. They catch only males. Such traps have “shown mixed results” according to the University of California Division of Agriculture and Natural Resources. They are most effective when your trees are at least a mile from other trees being used by codling moths (apples, pears, and walnuts). To use pheromone traps, start in early spring. Hang the traps in trees twenty to fifty feet away from your fruit trees. Hang one to four traps per tree (depending on the size of the tree) about six feet off the ground.4

The U.S. Department of Agriculture’s national sustainable agricultural information center recommends black light traps. These can be purchased, and attract both male and female moths.5 You can also use homemade traps that catch both male and female moths. Fill a plastic gallon milk jug with 1 cup vinegar, 1/2 cup molasses, 1/8 teaspoon ammonia, and 5 cups of water. Cut a 2 inch hole in the jug, just below its shoulder. Hang up to 3 traps per tree, depending on the size of the tree.4

Trapping Caterpillars

You can make simple traps for caterpillars from ordinary corrugated cardboard. Use a four-inch-wide strip and wrap it snugly around the tree trunk. The corrugation should be vertical (up and down the trunk). You can use staples to attach the cardboard to the trunk; it should be at least a foot and a half above the ground. Caterpillars will crawl under the cardboard and use the “tunnels” as protected spots to spin their cocoons. Once they have spun their cocoons, remove the cardboard and destroy it.4 The trick to using this method is timing it properly. You can catch the overwintering generation of caterpillars by putting up bands in August and destroying them between November and January.4 For other generations, watch the traps and destroy and replace them when you see cocoons.6

Bagging

In the early 90s, two California extension agents tested a novel pesticide- free technique for protecting apples from codling moth. The technique uses paper lunch bags to protect developing apples. Use the bags by cutting a two inch slit in the bottom of the bags. Put this opening over fruit when the fruit is between one and two inches in diameter and staple the open end of the bag closed around the fruit. Then leave the bags on the tree until harvest. The bags also protect the fruit from sunburn. Although the technique is time consuming, “for individuals with few trees, bagging can result in quality fruit without significant loss due to codling moth.”7

The Home Orchard Society has written hands-on advice about bagging apples with paper bags and even nylon footies. See resource list at the end of this article for links to this information.

Trichogramma Wasps

Trichogramma wasps are minute wasps that lay their eggs in moth eggs, including the eggs of the codling moth. When the wasp eggs hatch, the juvenile wasp eats the moth egg. Trichogramma wasps are available commercially. If you want to try using these wasps, release two or three batches one week apart when the moths start to lay eggs3(approximately mid-April in the Northwest1). The wasps are usually sold as pupae on little cards which you put in small cups hung in the tree. The wasps feed on nectar and pollen so will do best if there are flowers nearby.3

Birds

Woodpeckers have been observed eating significant numbers of codling moth caterpillars. These birds feed on the caterpillars after they leave the fruit at the end of the summer and during the fall when the larvae are in cocoons on the trunk of the tree. Other important codling moth predators are nuthatches and creepers.8

Codling Moth Virus

The codling moth granulovirus offers “potential for effective and selective control”9 of codling moth and “has been considered the most effective biological control agent ever tested against the codling moth.”8 The virus is available commercially and should be applied weekly for best results.8 According to their manufacturers, “inert” ingredients in commercial codling moth granulovirus products include glycerin, water, and insect parts associated with growing the virus.10,11

Conclusion

A wide range of nonchemical solutions for codling moth problems are available. By using a combination of the techniques summarized in this article, you can have worm-free and pesticide-free apples and pears in your backyard.

Home Orchard Society: Bagging resources

*****

Photos courtesy of Clemson University.

Codling Moth Traps & Refills Gardening Naturally

Assemble the trap. Place sticky insert sticky side up in the base of the trap. The pheromone lure (which looks like a hollow cone of soft rubber) should be removed from the foil sachet and laid in the centre of the sticky insert. Ensure that the end flaps are secured.

Note: The lure will release scent from when the sachet is opened – do not open sachet until the lure is needed.

In a garden one trap should monitor up to 5 average size trees with a range of 15 metres (50 feet) of the trap. It should be hung at around head height on the windward side of the tree (or group of trees).

After 5 Weeks – replace the sticky insert and lure. Inspect the trap regularly – the Codling Moth is small (about 8mm or 1/3rd inch long) dark coloured and rests with its wings folded to form a triangular shape.

If you are catching more than 15 moths per week the infestation is high and a suitable spray should be applied a week later. Continue monitoring and if again 15 or more moths are caught repeat the treatment.

Remove the trap by the beginning of September and dispose of the lure and sticky insert. The trap should be cleaned and stored. Refill Kits are available allowing the trap to be used for a second season.

How to optimize placement of pheromone traps in your orchard

Pheromone traps are an important IPM tool to track moth catches and evaluate pest pressure. Well-placed and maintained traps can greatly improve decision making when it comes to timing insecticide applications, and determining the need for insecticide applications to control codling moth (CM) and oriental fruit moth (OFM). Keep in mind however, that the traps are not a substitute for visual inspection of fruit to look for signs of infestation. Rather, trapping should be used in conjunction with inspecting fruit for injury.

MSU Extension’s Pocket Guide for IPM Scouting in Michigan Apples (E-2720 – purchase or view on-line) has information about scouting for both CM and OFM in apples. The Pocket Guide for IPM Scouting in Stone Fruits (E-2840 – purchase or view on-line) has detailed information about scouting for OFM in peaches.

There are several types of traps that can be used for monitoring CM and OFM including wing, diamond and delta traps. The plastic delta trap, discussed here, is probably the best option because it is reusable through several seasons, has a large trapping surface, and a removable sticky insert that is easy to replace when the adhesive surface becomes too dirty to catch moths. Traps are available in orange or white. The orange traps are less likely to attract and trap pollinators and other beneficial insects. If you decide to keep the traps to use for additional seasons, remove the spent lures, store traps that have been used for a particular pest species together and be sure that you reuse them for that same species the next year to avoid cross-contamination.

Never place more than one kind of lure in a trap, and avoid re-using the trap with a lure for another species. The pheromones penetrate the trap material, and using a different lure will cause failure of the lure.

One of the most common lures is a red rubber septum, which resembles a pencil tip eraser. The septum is pre-loaded with pheromone. After assembling the trap, an ingenious way of mounting the lure is to stick a 1.5 to 2 inch plastic- headed sewing pin straight down through one of the top sides, equal distance from both ends. Wearing disposable gloves, pick up the septum, reach inside the trap and stick the pin through the septum widthwise so it hangs horizontally above the bottom of the trap. Then mount all the lures of a single type, change gloves, and switch to the next lure you will need. Wear disposable gloves when handling the lures, and change gloves before you switch to mounting lures for a different species to avoid cross contamination. The sticky bottom can them be slid into the trap, and the side snapped into place.

OFM traps can be placed at a comfortable height for visual inspection. Avoid using outside tree rows for pheromone traps. Place OFM traps 3 to 4 rows in, at least 25 feet apart and at a density of 1 trap per ten acres.

Remove moths, other insects and debris from the trap each time you check it. Trap bottoms should be changed when they are dirty. Follow manufacturer’s directions for changing lures, but in general for OFM, change lures each generation. Used lures and lure packaging should be removed form the orchard, not dropped on the ground. Keep trap entrances clear of foliage. Hang bright, colored flagging tape (fluorescent pink works well) on the trees where the traps are located, on the end of the row and make a written reference or map for yourself so you can find the traps again as the season progresses.


Coding moth trap placement.

Traps for CM should be hung in the upper third of the tree canopy, on the periphery of the tree with the trap entrances oriented so moths can fly through. A bamboo pole or PVC pole can be used to position the trap high in the canopy. The length of pole needed will depend on the tree height and how high you can comfortably reach. For small to medium-sized trees a 5-6 foot pole should be long enough, but 8-foot or longer poles may be needed for taller trees. Drill a hole near the end of the pole to use for securing the trap. Compress the end of the trap’s wire hanger with a sturdy pair of pliers to enable it to slide through the hole in the bamboo pole, and then wrap the wire back around itself to secure the trap. Traps for CM are now ready to hang.

Find a branch high in the canopy to slip the trap over, and adjust it with the pole so that the trap hangs straight down. Once the trap is in place, hang bright, colored flagging tape (fluorescent pink works well) on the trees where the traps are located, and on the end of the row. Make a written reference or map for yourself in case the tapes get pruned off so you can find the traps again as the season progresses. Keep the trap entrances free of foliage so that moths can follow the odor plume and be lured into the trap. Leaves can be periodically pruned away as the foliage grows.

Traps for CM should be placed at a density of 1 trap/2.5 acres. Place CM traps 3 to 4 rows in and at least 25 feet apart. Remove moths, other insects and debris from the trap each time you check it. Trap bottoms should be changed when they are dirty. When lures are changed, remove both the old lures and the packaging for the new lures from the orchard. Follow manufacturer’s recommendations for frequency of changing lures.

There are several lures available that will last for different lengths of time. Some work better in pheromone disrupted orchards than others. High load lures, containing more pheromone, will need to be changed less frequently than standard lures. For codling moth, a combination lure has been developed that contains both pheromones and an ester present in the odor of ripe Bartlett pears. Called the CM/DA lure, it attracts both male and female CM, and has been found by MSU researchers to be useful in monitoring CM in orchards that have been treated with a mating disruption product. Either pheromone based CM lures or CM/DA lures can be used in non- mating disrupted blocks.

  • A Pocket Guide for IPM Scouting in Michigan Apples, D. Epstein and L. Gut, MSU Extension Bulletin, E-2720
  • A Pocket Guide for IPM Scouting in Stone Fruits, D. Epstein, L. Gut, A. Jones, and K. Maxon-Stein MSU Extension Bulletin, E-2840
  • Using pheromone traps to monitor moth activity in orchards. ipmnews.msu.edu/fruit May 19, 2009. Larry Gut, David Epstein and Peter McGhee

UC Pest Management Guidelines

| All apple pests | All crops | About guidelines |

Apple

Scientific Name: Cydia pomonella

(Reviewed 8/06, updated 12/09, pesticides updated 10/15)

In this Guideline:

  • Description of the pest
  • Damage
  • Management
  • Important links
  • Publication
  • Glossary

DESCRIPTION OF THE PEST

Codling moth has a 0.5 to 0.75 inch wingspan. The tip of each forewing has a coppery-tinged, dark brown band that distinguishes codling moth from other moths found in apple orchards. Females lay eggs singly on leaves and sometimes on fruit later in the season. The eggs are smaller than a pinhead, disk-shaped, and opaque white when first laid. Just before hatching the black head of the larvae becomes visible. Newly hatched larvae are white with black heads. Mature larvae are 0.5 to 0.75 inch long, pinkish white, with mottled brown heads. Depending on climatic conditions and location in the state, there are two to four generations of codling moth each year.

DAMAGE

Codling moth has the greatest potential for damage of any apple pest, yet it can be effectively controlled with properly timed treatments. It causes two types of fruit damage: stings and deep entries. Stings are entries where larvae bore into the flesh a short distance before dying. Deep entries occur when larvae penetrate the fruit skin, bore to the core, and feed in the seed cavity. Larvae may enter through the sides, stem end, or calyx end of the fruit. One or more holes plugged with frass on the fruit’s surface are a characteristic sign of codling moth infestation. Calyx entries are difficult to detect without cutting the fruit.

MANAGEMENT

An IPM program uses a combination of tools for codling moth management, including insecticides, mating disruption, and cultural controls. Mating disruption is the preferred tool because of its low toxicity to people, natural enemies, and the environment, but it may need to be supplemented with insecticide sprays, especially during the first few years. In orchards where codling moth is managed primarily with insecticides, alternate insecticides that have a different mode-of-action Group number to avoid the development of resistance. If you see trap catches increasing and suspect insecticide tolerance or resistance, combine the use of mating disruption with the insecticides. All codling moth management programs should be supplemented with cultural controls.

Alone, natural enemies are not able to keep codling moth populations below economic levels. Augmentative releases of the egg parasite Trichogramma platneri have been applied to reduce codling moth populations, but research has shown that this technique has limited effectiveness and is too expensive for practical use.

Remove host trees in nearby abandoned orchards (apple, pear, and walnut) to destroy reservoirs of codling moth. Also remove props, picking bins, and fruit piles from the orchard. Proper pruning and orchard sprayer calibration will improve spray coverage. An option for small, organic orchards is hand thinning to remove all infested fruit during each generation, before worms leave fruit, and removal of dropped fruit.

Organically Acceptable Methods

Organically acceptable tools for the control of codling moth include cultural control in conjunction with mating disruption and sprays of approved oils, codling moth granulovirus (Cyd-X), the Entrust formulations of spinosad, and kaolin clay (Surround). Check with your certifier about the exact status of all materials.

Monitoring And Treatment Decisions In A Mating Disruption Orchard

Degree-days

Calculate degree-days for codling moth in your location.

Learn to use degree-days to time insecticide applications.

Mating disruption works best in large, uniform orchards that are relatively square in shape. It is not recommended for orchards less than 3-5 acres in size. The larger the contiguous block of mating disruption, the more effective it will be. In orchards with moderate-to-high populations of codling moth and/or in the first year of mating disruption, insecticides or other supplemental controls will likely be needed in addition to the mating disruption program. Using mating disruption successively over a number of years can effectively lower the codling moth population so that alternative, reduced-risk chemical treatments can be effectively used to supplement control when needed.

Setting out pheromone dispensers

Pheromones are deployed as either hand-applied dispensers or in an aerosol canister (puffer). Sprayable pheromones are available but not currently recommended for pome fruit orchards because of their very short residual.

Using historical biofix dates to time the application, hang all pheromone products shortly before the first moth emergence in early March to early April. It is important to put out pheromone products early in order to disrupt the mating of overwintering moths as soon as they emerge. A late pheromone application will require supplemental spray treatment.

Place hand-applied pheromone dispensers in the upper third of the tree canopy. When placing puffers, put them on the inside of the canopy of edge trees or on the outside of trees in the second row. Upwind placement is one puffer every 50 to 65 feet, and downwind placement is one every 100 to 130 feet, or an average of 20 units per quarter mile. For large blocks, also place a few puffers towards the middle of the orchard on the upwind side. Reapply the dispensers according to the manufacturer’s guidelines if the product residual will not last through harvest or through the end of the last generation.

Monitoring with traps

Monitor pheromone-treated orchards with traps carefully to help ensure that mated moths have not moved in from adjacent orchards and that the pheromone is successfully disrupting mating.

Supercharged (10 mg) pheromone traps.

Place pheromone traps with supercharged (10 mg) pheromone lures in the orchard when pheromone dispensers are set out. Put these traps in trees at the same level as the pheromone dispensers. These traps serve to help set the biofix point for degree-day accumulation, which is used to time both fruit sampling and supplemental treatments. Check traps one to two times a week until biofix is set and once a week thereafter. Biofix is the first date that moths are found in traps for three consecutive checks and sunset temperatures have reached 62°F. (Replace lures at the frequency recommended by the manufacturer.)

Supercharged traps do not attract moths from far, so place as many traps as you can monitor in areas of the orchard that are known hot spots and areas vulnerable to wind where pheromone concentration is likely to be reduced. Examples include high spots and orchard edges; five to six rows inside the orchard is a good location. If the supercharged traps consistently catch high numbers of moths, monitor fruit in the surrounding area for eggs and damage to determine if a supplemental treatment is necessary. No thresholds have been established for these supercharged traps but 5 moths/week can be considered a relatively high trap count.

Regular (1 mg) pheromone traps

Another tool in a mating disruption program is the use of pheromone traps with the regular (1 mg) lures to verify the effectiveness of the mating disruption dispensers. A good idea is to pair a 1 mg trap with a supercharged one. Check traps weekly and replace lures at the frequency recommended by the manufacturer. The supercharged traps should catch a few moths, but the 1 mg traps should not catch any. If moths are caught in the 1 mg traps, check the fruit in the surrounding area. If eggs or damage are found, apply a supplemental treatment to prevent further damage. Traps with regular lures can also be used in upwind border trees (placed in trees in the second row) to monitor the influx and development of codling moth. When moths are caught in these edge traps, it signals the need to monitor fruit.

DA lures

A plant-derived chemical (kairomone) lure has been developed to assist in monitoring codling moth populations. This lure is sold commercially as the “DA” lure and is available alone and in combination with pheromone (“combo lure”). The DA lure has been shown to catch both female and male moths, whereas pheromone lures catch only male moths. The sex of moths caught in traps using the DA lure can be determined by observing the tip of the abdomen. If the moth is female, the abdomen can be squeezed to eject the bursa pouch and give some idea of whether the moth is unmated, mated once, or more than once. Generally, if the female’s abdomen feels hard to the touch, the moth is most likely mated.

The DA lure appears to work best in mating-disrupted apple orchards early in the season. The DA and DA/pheromone combo lure may also be used to assess the success of mating disruption in an orchard, similar to using a supercharged (10X) pheromone lure. Because these lures are relatively new to the market and there appears to be some variability in these lures from one season to the next, use them in conjunction with standard 10X and 1X pheromone lures in order to become familiar with them.

Fruit sampling

Fruit damage can occur even when no moths are caught in traps, so always check fruit for damage towards the latter half of each generation (900 to 1000 degree-days from biofix) and whenever moths are being caught in traps. Examine at least 200 fruit from throughout the orchard as well as in known hot spots and areas vulnerable to wind (edges, high spots), which can reduce pheromone concentration.

If fruit damage exceeds 0.5%, supplemental sprays should be used for the next generation. If the damage is quite light and very localized along a border, treating five to ten rows along the problem border may be adequate. However, if damage is not clearly localized, or is localized but more than a few percentages, then a larger area or the entire orchard may need to be sprayed.

Supplemental treatments
First generation

In orchards with moderate-to-high codling moth populations or if the orchard is in the first year of mating disruption, supplement the mating disruption with an insecticide spray of Altacor, Delegate, Assail, Imidan, or Warrior at 250 degree-days after the biofix to target hatching eggs from the first peak of the overwintered moth flight. If monitoring indicates continued flight, apply a second application about 600 to 700 degree-days from the biofix to suppress egg hatch from the second flight peak of the overwintered moths.

For low populations, applying a supplemental spray to the first generation may not be necessary. Use trap catch information and monitor fruit to determine if a spray is needed. Using a reduced risk material such as the IGRs (methoxyfenozide-Intrepid) or an organically acceptable alternative (oil, spinosad-Entrust, or codling moth granulovirus – Cyd-X) may be sufficient for control of low populations.

Second and third generation

To determine if treatment is needed for subsequent generations, careful trap and fruit monitoring is essential. If treatment is needed, use the guidelines in the section below to determine the best time to spray.

Monitoring and Treatment Decisions in a Conventional Orchard

In orchards where codling moth is managed primarily with insecticides, pheromone traps, in conjunction with degree-days and sunset temperatures, are used to determine egg hatch and proper spray timing. When using pheromone traps, keep in mind the many factors, such as tree size, trap density, type of trap, trap placement, brand of pheromone, as well as climatic conditions, that can affect trap counts.

Establish first biofix and begin accumulating degree-days

Hang 1 mg pheromone traps in the orchard in mid-March (or at bloom in foothill orchards) about 6 to 7 feet high, with one trap every 10 acres and at least two traps per orchard. The first date that moths are found in traps for three consecutive trap checks and sunset temperatures have reached 62°F is first biofix. (Service traps one to two times a week until biofix is set and once a week thereafter. Replace lures at intervals specified by the manufacturer.)

Spray timing

Once biofix is reached, calculate degree-days using a lower threshold of 50°F and an upper threshold of 88°F.

The most effective spray timing for each generation is outlined below. For all generations, if high levels of moths are being caught in traps, do not wait until 200–250 degree-days to treat, but apply the first spray at the beginning of egg hatch (160 degree-days).

Codling moth has two to four generations each season. Continue to monitor the generations with traps and accumulate degree-days until the crop is harvested or populations decline below damaging levels in September.

First generation egg hatch

Two to three sprays may be necessary to adequately control the first generation particularly if the population is high or a short-residual insecticide is used. In addition, if rainfall exceeds 0.5 inch or an irrigation with overhead sprinklers is scheduled within 2 weeks after treatment, a second spray will be needed. Apply the first spray when 250 degree-days have accumulated from the first biofix, unless high levels of moths are being caught, in which case spray at 160 degree days.

Make the second and third, if needed, application when the residual effectiveness of the previous spray has ended; this will vary, depending on the chemical used. If trap catches are low or the weather turns too cool for moth activity, you can delay treatment, but continue to monitor.

Second generation egg hatch

Use pheromone trap catches to detect an increase in moth flight activity around 1060 degree-days from the first biofix, which signals the start of the next flight and is the second biofix. For low moth populations, a single application may be sufficient; make this application when 200 to 250 degree-days have accumulated from the second biofix. If you are catching high levels of moths per trap per week, spray at 160 degree-days. If needed, apply a second spray when the residual of the previous spray ends. These two sprays should provide control during the entire egg hatch period.

Third generation egg hatch

A third generation of codling moth eggs does not occur every year in every location. Codling moth larvae normally go into diapause (winter dormant state) around August 22, but in warm years and warm locations they will have already started pupation before August 22, and these pupae will soon emerge as adults to produce a third generation. If 650 degree-days have accumulated between the peak of the second generation flight and August 22, most of the codling moth will not go into diapause but will pupate and emerge in August to early September, depending on climate.

If degree-day accumulation data indicates a third generation will occur, use pheromone traps to establish a third biofix point around 1100 to 1200 degree-days from the second biofix. Apply a spray when 200 to 250 degree-days have accumulated from the third biofix unless trap catches are high, in which case treat at 160 degree-days. If needed, apply the second spray when the residual of the previous spray ends.

Fourth generation egg hatch

In the hottest growing regions of the state, such as the southern San Joaquin Valley, a fourth or partial fourth generation may occur in some years. When flight activity increases around 1100 to 1200 degree-days from the third biofix, establish the fourth biofix. Apply a spray when 200 to 250 degree-days have accumulated from the fourth biofix and, if needed, a second spray when the residual of the previous spray ends.

Common name Amount per acre** REI‡ PHI‡
(Example trade name) (conc.) (dilute)
(hours) (days)
UPDATED: 10/15
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide’s properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
MATING DISRUPTION
A. MATING DISRUPTANTS
COMMENTS: Most effective in isolated blocks and larger blocks (more than 10 acres for hand-applied, more than 40 acres for aerosol dispensers) with low to moderate codling moth numbers and trees of uniform size and moderate height. Can also be used in smaller blocks to lower codling moth numbers over time. If used in smaller blocks, supplemental insecticides will likely be required. Apply just prior to first flight biofix in mid-March to mid-April. Reapply, if needed, at the interval recommended on the label. Hang 1 mg pheromone traps at 6 to 8 feet high in the canopy and assess them weekly to ensure the mating disruption product has not expired. Use traps baited with CM-DA combo lures high in the canopy to monitor population development. Check fruit for damage after each generation and treat with insecticides if needed to ensure a low level of damage at harvest.
Aerosol dispensers# Period of Effectiveness (days)
CheckMate Puffer CM-O 1–2 dispensers/acre 0 Up to 200
Isomate CM Mist 1–2 dispensers/acre 0 Up to 200
COMMENTS: Hang dispensers in the upper third of tree canopies at a spacing of one per 180 to 209 linear feet in trees around the perimeter. Within the orchard’s interior, place dispensers in a roughly square grid pattern to achieve an interior density of one per acre. The pheromone plume released by dispensers is large and has been shown to reduce 1 mg trap catches up to 2000 feet downwind. Use CM-DA combo traps (as well as standard 1 mg traps) to monitor conventionally managed orchards near orchards with aerosol dispensers to provide an accurate assessment of codling moth population and activity.
Hand-applied dispensers# Period of Effectiveness (days)
Isomate-C Plus 200–400 dispensers/acre 0 160+
Isomate-C TT 100–200 dispensers/acre 0 160+
Isomate-CM Ring 20–40 dispensers/acre 0 160+
CheckMate CM-XL1000 120–200 dispensers/acre 0 160+
COMMENTS: Attach dispensers to branches in the upper third of tree canopies. Apply dispensers individually in trees at a rate sufficient to give the recommended number of dispensers per acre. Hang lower density products such as the CM-Ring in a uniform pattern (e.g. every other tree in every row) to ensure even distribution of pheromone throughout the orchard. Make application shortly before first biofix.
INSECTICIDE CONTROLS
A. SPINETORAM
(Delegate WG) 6–7 oz 4 7
MODE-OF-ACTION GROUP NUMBER 1: 5
COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
B. CHLORANTRANILIPROLE
(Altacor) 3–4.5 oz 4 5
MODE-OF-ACTION GROUP NUMBER 1: 28
COMMENTS: Do not apply dilute applications of more than 200 gal/acre; use 100–150 gal/acre for best results.
C. ACETAMIPRID
(Assail 70 WP) 1.7–3.4 oz 12 7
MODE-OF-ACTION GROUP NUMBER1: 4A
COMMENTS: Larvicide; use in orchards with moderate-to-high populations. Begin applications 250 DD after biofix. Residual at 3.4 oz/acre rate is about 14 days. May cause outbreaks of mites, especially in orchards with chronic mite problems; addition of 1% oil (volume by volume) and limiting applications to a single application may help mitigate mite problems. Otherwise, to help prevent the development of insect resistance, limit applications to one generation per year. Repeat applications of any neonicotinoid insecticide (acetamiprid-Assail and imidacloprid- Admire Pro) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode-of-action Group number to help delay the development of resistance. To help prevent development of resistance, do not use for both codling moth and aphid control. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
D. PHOSMET
(Imidan 70W) 3.5–5.75 lb 7 days 7
MODE-OF-ACTION GROUP NUMBER1: 1B
COMMENTS: Larvicide; use in orchards with high populations. Make applications 250 after biofix. Residual at the 5.33 lb/acre rate with a pH of 5.5 is about 14 days. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
E. LAMBDA-CYHALOTHRIN*
(Warrior II with Zeon) 1.28–2.56 fl oz 24 21
MODE-OF-ACTION GROUP NUMBER1: 3A
COMMENTS: Larvicide; use in orchards with moderate-to-high populations. Make applications 250 DD after biofix. Residual at the 5 oz/acre rate is about 21 days. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
F. METHOXYFENOZIDE
(Intrepid 2F) 16 fl oz 4 14
MODE-OF-ACTION GROUP NUMBER1: 18
COMMENTS: Use only in orchards with low-to-moderate populations. Functions as a larvicide (must be ingested for it to be effective). Apply at 100 DD from first biofix and again in 10 to 18 days if flights are extended.
G. SPINOSAD
(Entrust) # 2–3 oz 0.67–1 oz 4 7
MODE-OF-ACTION GROUP NUMBER1: 5
COMMENTS: Use only in orchards with low-to-moderate populations or as a supplement to mating disruption. Tank mixing with 1% oil (volume by volume) increases efficacy: oil suppresses egg hatch and spinosad kills young larvae that ingest it. Apply 200 DD from first biofix, and reapply at 10-day intervals if continued coverage is needed. Do not apply more than 9 oz/acre per season. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
H. CYDIA POMONELLA GRANULOVIRUS#
(Cyd-X)# 1–6 fl oz 4 0
COMMENTS: Use only in orchards with low-to-moderate populations or as a supplement to mating disruption. A larvicide; larvae must ingest to become infected by this virus. Make first application at 200 to 250 DD. Make a second application 7 to 10 days later, a third application at 600 DD and a fourth 7 to 10 days later for a total of 4 applications per flight. The use of oil will help to provide increased control by distributing the virus better over leaf surfaces and serving as an ovicide by suffocating eggs. May also be tank-mixed with acetamiprid (Assail) for increased efficacy of both materials. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i.
I. NARROW RANGE OIL# 1–1.5 gal 4 when dry
MODE OF ACTION: Contact including smothering and barrier effects.
COMMENTS: Best used as a supplement to mating disruption and where population pressure is quite low. Functions as both an ovicide and larvicide. Oils are mildly effective against codling moth eggs and work by smothering them; they need to be reapplied frequently during egg-laying period, which is anytime moths are flying. Begin oil applications at 100 to 200 DD after the biofix. Reapply every 7 to 10 days as long as significant flight is occurring. Good coverage is essential. Effectiveness may be enhanced with more dilute applications (i.e., 200–400 gal water/acre). Oils may be phytotoxic if used within a few weeks of a sulfur or captan spray or if applied at higher rates during hot weather (above 90°F). May be used to maintain lower populations in mating-disrupted orchards. May cause a greasy appearance to some fruit if applied close to harvest or with high seasonal volumes. Check with certifier to determine which products are organically acceptable.
** For dilute application, rate is per 100 gal water to be applied in 300 to 500 gal water/acre, according to label; for concentrate applications, use 80 to 100 gal water/acre or lower if the label allows.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
* Permit required from county agricultural commissioner for purchase or use.
# Acceptable for use on organically grown produce.
Not recommended or not on label.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode-of-action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee).

IMPORTANT LINKS

  • Degree-day table
  • Degree-day calculator
  • Sunset temperatures
  • Using degree-days to time insecticide applications

PUBLICATION

UC IPM Pest Management Guidelines: Apple
UC ANR Publication 3432

Insects and Mites

L. R. Wunderlich, UC Cooperative Extension, El Dorado County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
P. M. Vossen, UC Cooperative Extension, Sonoma/Marin counties
L. G. Varela, UC IPM Program, Sonoma County
J. A. Grant, UC Cooperative Extension, San Joaquin County

Acknowledgment for contributions to Insects and Mites:

H. L. Andris, UC Cooperative Extension, Fresno County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
W. W. Coates, UC Cooperative Extension, San Benito County
C. Pickel, UC IPM Program, Sutter/Yuba counties

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Codling moths

How to protect your garden from codling moths

If you have never had a codling moth problem in your orchard, then you would probably have low numbers of this pest.

Keep your garden or orchard clean

  • Pick up and remove any fallen apples throughout the growing season and after harvest and place them in the trash.
  • Do not throw away apples in places where you also store apples.
  • Inspect your crates and the storage building for cocoons and destroy the insects.
    • Harvested apples may contain codling moth larvae, that might exit the fruit and seek shelter in the storage area.
    • Storage structures like a garage or barn may be a source of codling moths the next spring.
    • Wooden apple crates provide shelter for the larvae in winter.

Codling moth adults can fly as far as a mile to find mating sites on apple trees. If you live in an area where codling moths are common, maintaining cleanliness will not be enough.

Trapping codling moths

Codling moth trap

Codling moths are trapped using a tent-shaped plastic or waxed-paper trap, hung in a tree. The most common are “delta” traps or “wing” traps.

On the inside, the trap is coated with tanglefoot (made up of a natural, sticky substance). A lure that gives off artificial female pheromones is used as bait. Male moths seeking a mate fly into the trap and get stuck in the tanglefoot.

  • In early May, hang the trap at about eye level on the outside of the tree canopy.
  • Check the trap weekly starting in mid-May, to see if you have codling moths in your area.
  • Clean out the moths and any other insects each time you check the trap.
  • If you don’t catch any codling moth adults, you might not require pesticide sprays to control them.
  • Lures are effective only for one or two months.

Always use a pair of tweezers used only for handling codling moth lures, or use disposable gloves. Otherwise, you may transfer attractant pheromone to surfaces other than the trap.

See Pest management for the home apple orchard, for information about where to buy trapping materials.

Using pesticides

If you trap codling moths, treat your apples soon after the first flight has begun.

  • The best time to spray is when most or all of the petals have fallen from the apple blossoms.
  • Do not treat before this as the sprays will be ineffective and will also kill pollinating bees.
  • Make a second spray, 7 to 10 days later.

Chemicals that control codling moth include spinosyn, carbaryl, esfenvalerate and malathion.

If you want to control codling moth and apple scab at the same time:

  • Mix pesticide and fungicide in the same tank, or
  • Use a pre-mixed all-purpose fruit spray that does not contain carbaryl.

CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.

Be sure that the fruit/vegetable you wish to treat is listed on the label of the pesticide you intend to use. Also be sure to observe the number of days between pesticide application and when you can harvest your crop.

Jul 10, 2018How to fight hard-to-kill codling moths in apples

The early bird gets the worm, and growers who prepare early will have more luck catching codling moth before it damages their apples.

Insecticide sprays must be timely, based on traps tracking moth flights, and the traps need to be set well in advance. A diversity of insecticides should be chosen so that pests don’t evolve resistance to an over-used spray. And even non-chemical control techniques, such as pheromone disruption, require good planning.

A codling moth larva. Photo: Todd Gilligan, LepIntercept, USDA APHIS ITP, Bugwood.org

Timely sprays

There’s a narrow window of opportunity to hit codling moths with insecticide sprays.

A delta-shaped trap – tent-shaped trap with pheromone and a sticky pattern – can help growers pinpoint the right time. The trap will measure when the moths begin flying and application of insecticides will soon follow. Adama Agricultural Solutions Development Sector & Insecticide Leader Diane Silcox Reynolds said it’s important to spray as soon as moth flights are detected.

“You want to be tracking and monitor your moth flights,” Reynolds said. “The moth will lay those eggs either directly on the fruit or on the leaf very near to the fruit, and those eggs hatch and the caterpillars immediately start to crawl and burrow and feed on the apple,” she said. “You have a very narrow window of when that happens. So, you want your product out before that happens.”

Avoiding resistance

Apple growers may apply insecticide with an airblast sprayer six to eight times during the season as codling moth moves through three to five different generations, Reynolds said.

Those sprays should be chosen carefully. Codling moth has a documented history of developing resistance to insecticides but cycling through different sprays with different mechanisms of action can reduce the risk of that.

Adama’s go-to spray for codling moth is Cormoran, a relatively new spray that debuted in late 2016, and has two active ingredients or mechanisms of action: Novaluron, an insect growth regulator, and Acetamiprid, a neonicotinoid that works on the moths’ nervous systems. But Reynolds recommends using a different spray for each generation of codling moth during the season and making sure the sprays have different modes of action. For example, a spraying schedule could start with Cormoran with the first moth flight, then during the second generation or brood, FMC’s Altacor, which works on the moth’s muscles, and in the third generation move to Dow AgroSciences’ Delegate, which like Acetamiprid works on the moths’ nervous systems, but hits a different site.

“If you use the same product you’re going to select for the ones that are resistant to the product,” Reynolds said. By hitting the bugs with a variety of chemicals, “you’re reducing the overall number of resistant moths in a population,” and decreasing the likelihood of the resistant bugs breeding together.

An adult codling moth. Photo: Todd M. Gilligan and Marc E. Epstein, TortAI: Tortricids of Agricultural Importance, LepIntercept, USDA APHIS ITP, Bugwood.org

IPM options

Non-chemical controls of codling moth include mating disruption by aerosol dispensers of codling moth pheromone.

“It fills the orchard with that pheromone and so the moths aren’t able to find each other, because that pheromone is everywhere, instead of in a concentrated area where that moth would be,” Reynolds said. “They call it mating disruption because they can’t find each other to mate.”

Washington State University’s Decision Aid Systems website advises using oil sprays to kill moth eggs, and even adding codling moth granulosis virus to the oil sprays. More information is available online.

Codling moth damage to apples. Photos: Ward Upham, Kansas State University, Bugwood.org

Outlook

The stakes are high for apple growers. A single worm burrowing into an apple makes it unmarketable for fresh sales and can even hurt processing sales.

“Your damage threshold is so low, that growers will still make insecticide applications,” Reynolds said. “Anytime you have a caterpillar in your apple, even if it’s for juice, that could still decrease your quality and ultimately how much you get paid.”

In the Pacific Northwest, “we would anticipate pressure to be similar to last year,” she said. “From what I’ve heard, they’re having an early spring again this year, so we would expect when you have an early spring that you will be battling codling moth for much longer in the season.”

– Stephen Kloosterman, FGN Assistant Editor

Organic methods to control codling moth

Not what we want to eat

Bugs are a part of nature. I come in peace, but when they invade an entire apple crop, its time to declare war.

Words: Sheryn Clothier

I run my orchard as closely aligned with nature as possible. That means I use very, very few sprays (even organic ones) as I believe in allowing the natural balance to assert itself. If my fruit aren’t all perfect, so be it, as long as there are enough.

This practice works well in theory. The problem is fruit trees aren’t in New Zealand’s natural balance. They are relative newcomers to our ecosystem and all their pests and diseases that have come in with them are relative newbies too. This means they may not have natural predators here.

Codling moth (Cydia pomonella) is one such pest. It infests all pipfruit (apples, pears, quince, crabapples, nashi) and walnuts. The caterpillar feeds for three weeks inside the fruit. Signs are an infected core and access hole ringed with brown frass (residue from chewing or excrement).

There are several organic methods to control codling numbers in your orchard. Unfortunately, some commonly-known ones are not particularly effective and all the methods target different stages of the life cycle so it is important to be doing the right one at the right time of year.

Cardboard wraps are limited in their effectiveness

Winter

During winter the pupae spin a silken cocoon in a crevice or under bark and await temperatures of 15°C.

STRATEGY: REMOVE AND DESTROY PUPAE
Clean up all fallen fruit and litter from under the trees. You don’t want any hidden habitats they can overwinter in.

Having chickens running under the trees may seem a solution, but carabid beetles and disease will kill any codling on the ground. Those who have trees both in and outside their chicken pen say there is no difference in the codling levels.

One remedy is to wrap the tree trunk in corrugated cardboard. The theory is that the caterpillar will find it an attractive hidey hole and spin their cocoon in there. You can then remove and burn it before they hatch in spring.

The problem is there are lots of places further up the branches they can choose to hibernate and there can be several generations a year.

To be most effective, place the cardboard as high up the trunk as possible (but below any fruit), grease or make a sticky band below the cardboard to stop them passing on by, and remove and burn frequently from early summer to after harvest. Even then, you will only get a proportion of the codling cocoons.

Cydia pomonella larva Photo: Peggy Gregg

Spring

This is the start of their active life cycle. Once the blossoms start showing a pink colour, the pupa develops the features of an adult moth and emerges late in spring (about petal fall). Adults will continue to emerge for several weeks and are most active on warm evenings.

They will mate and the female will singularly lay tiny eggs (about 1mm long) on or near developing fruit. These eggs take 8-14 days to hatch into tiny larvae which then crawl inside the fruit. This period is the most effective time to attack.

STRATEGY 1: DISRUPT MATING WITH PHEROMONE TRAPS
Pheromone traps are commonly available at garden centres or hardware stores. They have a lure, a sticky trap base and a triangular cover to hang in the tree. These use the female mating scent to attract males.

To use them as a form of control is like putting a pub on the corner and hoping it will stop teenage pregnancies. Males can mate many times and a mated female can lay as many as 200 eggs. You would have to trap every male as a virgin to be effective.

However the traps are a useful way to monitor when the moths are active (so you can spray). They are only effective if the sticky base is sticky and dust can quickly coat them. Fold them in half and then re-open to restore the sticky tendrils and extend their effectiveness.

PHEROMONE DISRUPTORS
Organic pheromone mating dispensers are a twist tie that you slip over a branch at the beginning of the season. When applied at 100 to the hectare, they release the female scent to such a degree it confuses the male and prevents mating. Moth numbers should fall in the sticky base trap if they are working effectively.

However, these are not easy to source, and although well regarded, I tried them for two years running with little noticeable effect. However, I had three closely-planted apple trees that are badly infected, and these are apparently more effective when used with low density of codling spread over a wide area/larger orchard.

STRATEGY 2: TRAP ADULT MOTHS
See method under summer strategies.

STRATEGY 3: KILL THE EGGS
Neem oil, conqueror oil or any oil spray will smother and kill the eggs. To be effective, this must be repeated at eight day intervals until your traps show the adults have stopped flying and laying, and full cover of the eggs must be achieved – spray under and over.

I presume the oils will also kill every other living being on your tree while you are at it so this is not a strategy I practice.

STRATEGY 4 KILL THE EMERGING LARVAE BEFORE IT ENTERS THE FRUIT
This needs to be done at approximately 80% petal fall, and needs to be repeated for success.

You can use any spray at this stage that is effective against caterpillars. Be aware that organic pyrethrum sprays and homemade garlic sprays will also affect beneficial insects, including your pollinating bees.

There are two organic sprays which are more specific, available at garden centres. You can get a sachet of Kiwicare’s organic caterpillar biocontrol. It does not list the codling as a target (it is aimed at white butterfly, leaf rollers, looper and other caterpillars) but the Bacillus thuringiensis (BT) it contains is also very effective against the codling caterpillar.

The other is available through horticultural supply stores and is branded as Madex-3. This contains the Cydia pomonella granulises virus which is specific to the codling moth. It comes in 100ml to mix in 2000 litres to do a hectare and costs around $125 so is only economical for those with larger orchards, or you could band together with friends to purchase a bottle.

Spray 10 days after the monitoring traps start trapping moths, and again every 10 days until 10 days after the traps are no longer catching anything. In my climate, this equals 2-3 times at 10-day intervals from approximately 80% petal fall.

Once the caterpillar is inside the fruit it is protected from sprays.

Summer

The caterpillar will spend about three weeks gorging itself on the flesh of your apple, before emerging to seek a hidey hole to make its cocoon (see Winter). North of Auckland, they commonly hatch a second generation about November and theoretically they can have more generations in one year depending on the temperatures. Further south, the records show it to be more a single long stretch of activity.

Use traps to monitor and spray larvae 10 days after peak periods, and/or to catch adult moths.

Once the caterpillar is inside the fruit, it is protected from any spray you useSTRATEGY: TRAP ADULT MOTHS
Moth traps can be used to significantly reduce numbers. While these have proven somewhat successful for me in the past, they were not effective enough in themselves for adequate control and there is no way to ensure you catch the female before she has laid her eggs.

However, gardeners I know have found them to be very effective, almost totally eradicating codling within three years, and they swear by them. I found all these options equally effective.

You need to put them out by mid-blossom and maintain them until after harvest in March to catch as many moths as possible. You can note the fluctuations in numbers and use these as indicator traps (spray for larvae 10 days after peak periods) as well. You will need to clean and replenish them frequently.

A sophisticated light trap using a light under a lamp shade, over a dish of water

LIGHT TRAPS
Moths are attracted to light. Any light or solar light seems to work, although LED blue/white lights are said to be better than yellow-hued lights.

A container of water with a little cooking oil floating on top under the light will catch the moths. I have seen everything from corded lights under a Chinese-hat lampshade over a shallow dish, to cheap solar lights with their lens as the container.

A sweet mix in an old milk bottle

HOW TO MAKE A MILK BOTTLE TRAP
Cut an opening in the side of the milk bottle and fill with either of the following recipes – both work. Check after rain and clean out and replace as needed.

  • Recipe 1
    Mix 1 litre of warm water with 100g sugar (white or brown), 1 tsp Marmite, ½ tbsp cloudy ammonia and ½ tbsp vanilla and place in milk bottles with
    an opening cut in the side.
  • Recipe 2
    Put 1 tbsp of vinegar and 1 tbsp of treacle or molasses in a milk bottle with an opening cut in the side and half fill with warm water.

Little wax-eyes will dig out pupae

HOW NATURE CONTROLS CODLING MOTH
Natural controls have not proved effective in New Zealand. Yet.

Little wax-eyes (Zosterops lateralis, also known as silver eye, white eye) will dig out over-wintering pupae, but it’s not usually enough to be an effective control.

A parasitic wasp specific to codling was released in New Zealand in 1906. It has survived (in unsprayed orchards), but it has not killed enough codling to reduce the population.

Since 2012, Plant and Food Research has been releasing Mastrus ridens, another wasp which will lay its parasitic eggs in the eggs of the codling moth. Over 60,000 have been bred and released in the commercial apple regions of Hawkes Bay, Nelson/Motueka and Central Otago.

Removing any fruit you find with tell-tale brown ‘frass’ around the entry hole helps to control numbers

SHERYN’S RECOMMENDED ORGANIC CONTROL FOR HOME ORCHARDS
• Hang moth traps in the tree as soon as blossoms start to appear.
• Spray with a caterpillar biocontrol a week to 10 days after traps start catching adult moths or at 80% petal fall. Repeat in 10 days.
• Refresh traps and leave out to monitor for another generation later on in summer.
• Early season infection of the fruit is often by way of the catlyx and can be hard to see. However the caterpillar can be active inside the fruit as indicated by brown frass around the tell-tale hole. Removing and disposing of infected fruit can help control numbers.

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This article first appeared in NZ Lifestyle Block Magazine. Discuss This Article

How to Control Codling Moth on Apple Trees

Digital Vision/Digital Vision/Getty Images

The codling moth is the inspiration for cartoons that depict an apple with a cutesy worm poking through it. In real life, the codling moth larva is a serious pest on apple, pear and English walnut trees. It chews its way to the fruit core or young walnut meats, making both fruits and nuts inedible; damaged nuts usually fall from the tree well before maturity. After it takes up residence inside, the codling moth larva lives in the fruit for three weeks, stuffing itself with the apple’s flesh. Once it becomes an adult, it crawls back out into the world — falling off the tree before climbing up the tree trunk to form a cocoon and await transformation into a moth. Begin by controlling the codling moth with natural nontoxic options. If they fail, try synthetic chemicals.

Examine your trees for signs of larvae holes weekly. If larvae are eating your apples or pears you’ll see some crumbly brownish-red plant material — which the larvae excrete from their orifices as they digest fruit — around holes on fruit skin. Pick and discard all apples that appear infested to interrupt the moth’s reproduction cycle. In addition, remove fallen fruit off the ground.

Hang codling moth traps in the apple tree in early spring, to know when codling moths are active. Traps have pheromones — chemical substances that animals produce and release to attract a mate — that lure unsuspecting codling moths looking for romance. Once inside, the insects get stuck to the trap’s sticky bottom. Use two traps per tree, and place them on the tree’s highest branches. Scrape the dead moths off the trap bottoms once a week to keep the sticky area exposed. Replace the bottom with a new one every month.

Measure the tree trunk and branches, and cut pieces of corrugated cardboard the right size to wrap around them. Install the cardboard collars tightly around the tree’s limbs and trunk in May or later (depending on the moth’s life cycle in your area). Use heavy-duty duct tape to keep these covers in place. Don’t staple them to the wood as other pests might find their way into the tree through the holes left. Unable to reach the bark, the codling moth larva will weave its cocoon on the cardboard. Once this happens, remove and discard the trunk and branch collars.

Spray your apple tree with an insecticide that contains phosmet, if needed. Treat the plant with it every two weeks. Begin to spray two weeks after the pheromone trap catches its first moth.

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