- common name: cottony cushion scalescientific name: Icerya purchasi Maskell (Insecta: Hemiptera: Margarodidae)
- Distribution (Back to Top)
- Description (Back to Top)
- Host Plants (Back to Top)
- Economic Importance (Back to Top)
- Management (Back to Top)
- Selected References (Back to Top)
- Tea Scale
- Tea Scale
- Cottony Camellia Scale on Holly
- Cottony Camellia Scale
- Trees at Risk
- Signs of Damage
- Physical Appearance
- Treatment Strategy
common name: cottony cushion scale
scientific name: Icerya purchasi Maskell (Insecta: Hemiptera: Margarodidae)
The cottony cushion scale was described by Maskell (1878) from specimens sent to him by Dr. Purchas from Auckland, New Zealand. The host was kangaroo acacia and the insect was named for Dr. Purchas. At that time only one other species was known in the genus Icerya (Maskell 1878). This scale is apparently native to Australia and made its way to California on acacia plants around 1868 or 1869 and in about ten years was causing damage to citrus groves in southern California (Ebeling 1959). New control methods used first in California and later the rest of United States led to the implementation of biological control and legislative quarantine (Ebeling 1959).
Figure 1. Several life stages of the cottony cushion scales, Icerya purchasi Maskell, on a twig. Photograph by Paul M. Choate, University of Florida.
Distribution (Back to Top)
The cottony cushion scale is now widespread throughout the world wherever citrus is grown (Ebeling 1959). In Florida, this scale has been reported from most counties.
The following account of the introduction of this scale insect into Florida is largely taken from Gossard (1901). The vedalia beetle, Rodolia cardinalis (Mulsant), was introduced into California in 1888 for the biological control of the cottony cushion scale (DeBach 1973). In 1893, the owners of a nursery in Keene, Florida (Pinellas County) sent an inquiry to someone in California about the possibility of the vedalia beetle (a ladybug) being used to control other scale insects in Florida.
Apparently interpreting this as a request for the ladybug, the California party sent a shipment of these ladybugs and included some cottony cushion scales as food for the ladybugs. The nursery owners, who either did not see the scales or assumed they would be of no consequence, left the packing container near a citrus tree which eventually became infested. The originally infested Florida trees were destroyed, but infested trees appeared again in late 1898. However, this was presumably from a new introduction from nursery stock in about 1895 (Gossard 1901).
Figure 2. Adult vedalia beetles, Rodolia cardinalis (Mulsant), feeding on cottony cushion scale, Icerya purchasi Maskell. Photograph by Division of Plant Industry.
Description (Back to Top)
The cottony cushion scale can be distinguished easily from other scale insects in Florida. It is the only species of Icerya present in Florida. The mature females (actually hermaphrodites) have bright orange-red, yellow, or brown bodies (Ebeling 1959). The body is partially or entirely covered with yellowish or white wax. The most conspicuous feature is the large fluted egg sac, which will frequently be two to 2.5 times longer than the body. The egg sac contains about 1000 red eggs (Gossard 1901).
Figure 3. Adult female cottony cushion scale, Icerya purchasi Maskell. Photograph by Division of Plant Industry.
Depending on the temperature, eggs hatch in a few days to two months. The newly hatched nymphs are bright red with dark antennae and thin brown legs. The antennae are six-segmented. This is the primary dispersal stage. Nymphs can be wind-blown to new locations, crawl to nearby plants, or possibly hitchhike on other animals. After three molts the adult begins to deposit eggs and secrete the conspicuous egg sac. As the egg sac is formed the scale’s abdomen becomes more and more tilted until the scale appears to be standing on its head.
Figure 4. First instar crawler of the cottony cushion scale, Icerya purchasi Maskell. Photograph by Lyle J. Buss, University of Florida.
Figure 5. Early nymphal stage of the cottony cushion scale, Icerya purchasi Maskell. Photograph by Lyle J. Buss, University of Florida.
Figure 6. Various nymphal stages of the cottony cushion scale, Icerya purchasi Maskell. Photograph by Lyle J. Buss, University of Florida.
Males are rare. They are winged with a dark red body and dark colored antennae. Dark whorls of setae extend from each antennal segment, except the first (Ebeling 1959). It is interesting that the female is always a hermaphrodite with both testes and ovaries. If self-fertilization occurs only hermaphrodites are produced; however, when a hermaphrodite mates with a male, more males and hermaphrodites are produced (Ebeling 1959).
Host Plants (Back to Top)
Cottony cushion scale is most frequently collected on Citrus and Pittosporum in Florida. However, numerous records on other host plants are in the Division of Plant Industry insect files.
Economic Importance (Back to Top)
The cottony cushion scale can severely damage trees, resets, and nursery stock. Decreased tree vitality, fruit drop, and defoliation result from the feeding of this scale. Most damage occurs from the feeding of the early immature stages of the scale on the leaves, where they settle in rows along the midrib and veins, and on the smaller twigs. The older nymphs continue to feed, but migrate to the larger twigs, and finally, as adults, they settle on the larger branches and trunk. This scale is seldom found on the fruit. Added damage can result from the accumulation of sooty mold due to the honeydew excreted by the scale.
Management (Back to Top)
2014 Florida Citrus Pest Management Guide: Soft-Bodied Insects Attacking Foliage and Fruit
Selected References (Back to Top)
- Baker JR. (2005). Cottony cushion scale. Department of Entomology Insect Note. (7 April 2017)
- Debach P. 1973. Biological Control of Insect Pests and Weeds, Chapman and Hall, London. 844 p.
- Ebeling W. 1959. Subtropical Fruit Pests. University of California Press, Los Angeles. 436 p.
- Gossard HA. 1901. The cottony cushion scale. Florida Agricultural Experiment Station Bulletin 56:309-356.
- Grafton-Cardwell EE. (2003). Cottony Cushion Scale. UC/IPM Online. (7 April 2017)
- Maskell WM. 1878. On some Coccidae in New Zealand. Transactions and Proceedings of the New Zealand Institute 11: 220-223.
- Morrison H. 1928. A classification of the higher groups and genera of the coccid family Margarodidae. USDA Technical Bulletin 52: 203-211.
- Weeden CR, Shelton AM, Li Y, Hoffman MP. (2005). Rodolia cardinalis (Coleoptera: Coccinellidae), Vedalia Beetle. Biological Control: A Guide to Natural Enemies in North America. (no longer available online)
As with all scale insects, the females do not have wings and look similar to the immature stages. Immature cottony cushion scales have black limbs and an orange-brown body that is coated with white and yellow wax. The adult ‘females’ are easily recognized by their large size (up to 10 mm long), red-brown body colour and covering of granular, white wax. The legs, antennae and body hairs are conspicuously black. The nymphs and adult females produce long, hair-like, transparent rods of wax from the body. On reaching maturity, the ‘female’ produces a white, fluted, wax ovisac with a series of uniform ridges running lengthwise over the surface. The ovisac may reach the same length as the body, giving an overall combined length of up to 20 mm.
The ‘females’ are actually hermaphrodites with fertilization occurring between the eggs and the sperm of the same individual. Males are occasionally produced from unfertilized eggs, but mating is not necessary for reproduction. The adult male has well developed antennae and one pair of dusky wings,
The adult ‘females’ produce 500 to 2000 bright-red, oblong eggs over a period of 2 to 3 months. After leaving the egg sac, the crawlers settle along the midribs and veins of the leaves. The next two instars migrate to the larger twigs and branches and eventually moult into the adult ‘female’. There are two to four generations per year.
Damage caused by scale insects is usually serious, but not deadly to the camellia plant. If the problem goes undetected for a long period of time with no treatment it is possible for all or part of the plant to be killed. Camellias infected with scale insects appear unhealthy and produce very little new growth. Scale insects that attack foliage are usually seen on the underside of the leaf. Symptoms on the upper leaf surface appear as chlorotic areas. Heavily infested leaves will often drop off. Other types of scale insects attack twigs and branches and may cause death when infected severely.
Scale insects appear very different from many other types of insects. They are usually quite small and have sucking mouthpieces with which to feed on plant juices. Scales are divided into two groups – the armored scales which have a hard protective covering that is not an integral part of the insect’s body and the soft scales in which the waxy secretion is a part of the body.
Armored scales which attack camellias include the Florida Red Scale, Chrysomphalus aonidum; Tea Scale, Fioriniae theae; Oyster Shell Scale, Lepidosaphes ulmi; Camellia Scale, Lepidosaphes camelliae; and Greedy Scale, Hemiberlesia rapax. The adult female varies from 1/12 to 1/8 inch in length. Adult males generally are small, two-winged gnat-like insects which are seldom seen. An exception is the tea scale where adult males are white in color and more conspicuous than females. The female scale insect lays her eggs under the scale covering which hatch in 1 – 2 weeks.
The newly hatched scale, known as a crawler, has the ability to move about the plant to find succulent new growth. After about a week it inserts its mouthparts into the plant tissue. If it is a female it remains there for its lifetime. Crawlers can spread from plant to plant with the wind. They will attach a silk strand to the plant, raise their tails, and blow away with the wind.
Because insecticides are much more effective against the crawler stage of the scale life cycle applications should be timed to coincide with this stage if possible. The adult stage is usually reached 5 – 11 weeks after eggs hatch and there may be several overlapping generations each year. The crawler stage is observed in the spring.
Soft scales are larger than the armored scales and vary from 1/12 to 1/4 inch in length. The number of eggs per female range from 100-1000 and these hatch in 1 – 3 weeks. Some soft scales may bear their young alive. The newly hatched crawlers move about the plant for a few days to several weeks before attaching to feed. Soft scales develop slowly and it may be several months to a year before the females become adults. The different softscales that attack camellias include the brown soft scale, Coccus hesperidum; Hemishpherical scale, Saisettia coffeae; and the Cottony Camellia Scale, Pulvinaria floccifera.
Scale insects can be controlled by proper culture and use of insecticidal sprays. Plants should by spaced to allow air to circulate between them and pruned to open them and allow air to circulate through them. This will aid in the reduction of insect populations.
Petroleum oil sprays are environmentally friendly and they are non-toxic to humans or pets. They are effective only if sprayed directly onto the insect because they work through suffocation. Applications are usually made during the spring after bloom and in the fall prior to blooming. Spring applications will greatly increase mortality of scale crawlers. There are other more toxic insecticide sprays which can also be used. Consult the label for specifics.
Aply two types of controls (read the label and make sure that the active ingredient is different) so the scale insects will not get used to applications of a single insecticide.
- Oil emulsion sprays will give you effective control if applied early in the morning on days when the temperatures are mild (45-85 F).
- Systemic insecticides like Cygon and Orthene can also control tea scale.
- Contact insecticides like Malathion, Dursban and Sevin are very effective but repeat applications may be necessary.
The Landscape Alert: April is the Time for Tea (Scale Control)
by Willie Chance, UGA Center for Urban Agriculture and Kris Braman, Professor, UGA Entomology Department
Tea scale is the most serious insect pest of flowering camellias. Tea scale also attacks hollies, citrus and the tea plant (Camellia sinensis) as well as a few other plants.
Tea scale is a small insect that attaches itself to the leaf and sucks plant juices. Adult female tea scales are about 1/10 inch long and are covered with a hard brown cover. The males produce white waxes that cover their bodies. In heavy infestations, these white waxes make the underside of the leaf appear cottony. Affected leaves will develop yellow blotches on the upper surface. Heavily affected plants may be thin and unsightly and have fewer blooms.
In the spring, the next generation of scales hatches from eggs and move to find succulent leaves. These young, mobile scales are yellow and called ‘crawlers’. The scales attach themselves to the underside of leaves, begin feeding and develop their waxy, protective covers.
The timing of the first generation of crawlers is important since this is the best time of year to treat tea scale with insecticides. The time of emergence of the first generation of crawlers is dependent upon temperature and can vary greatly from year to year. For example, the first emergence of tea scale in Athens, GA has been as early as the first week of February (1999) and as late as the first week of May (1997). March and April are the most typical months for emergence in Georgia.
Tea scale crawler emergence timing for your area can be estimated based upon the time of flowering of certain plants. Tea scale crawler emergence occurs about the same time as the beginning of bloom for honeysuckle or tulip poplar, the time of 50% bloom for Chinese wisteria or sugar maple or when the weeds henbit and chickweed are blooming. Begin first crawler sprays for tea scale when you see these events.
Another method of timing crawler sprays is by looking for the crawlers themselves before spraying. Place pieces of double sided sticky tape on small stems. The sticky tape will capture the crawlers as they emerge and make them easier to see. Begin sprays when you find crawlers stuck on the tape.
There are several generations of tea scale in Georgia each year. Female scales lay eggs for several weeks and these eggs hatch continually. Later in the season, landscapers may find all stages of the tea scale life cycle on the plant at the same time.
Several factors make tea scale control difficult. Tea scale infestations often develop on the interior of the plant and may not be noticed until the infestation is heavy. It is difficult to get sprays into the interior of the plant and on the underside of the leaves where most tea scales are found. The scale’s waxy covers make adult scales very difficult to control with pesticides. Crawlers are much easier to kill but pesticide application must be timed to crawler emergence.
For best control
Adult scales are very resistant to insecticides. Time insecticide treatment to correspond to the first emergence of crawlers. Use the information mentioned earlier under ‘Tea scale crawler emergence timing for your area’ to decide when to begin treatment. Apply insecticides so that they cover the bottom surface of the leaves. Repeat treatments may be needed with heavy infestations. Select insecticides from the Pest Management Handbook. rune out heavily infested branches. Remove 2 to 4 inch long non-flowering branches on major limbs inside the plant since these can harbor scale.Thin the plant by removing selected branches. This can improve control by increasing air circulation and improving pesticide penetration into the plant.
Light to moderate infestations can be treated with oil sprays. Oil sprays are effective against crawlers and adult scales. There are two types of oil sprays – those that are used in the cooler weather of spring and fall and the highly purified oils that can be used during the growing season. Read and follow all label directions to select the correct oil spray. Cover scales very well when using oil sprays since oils work by smothering the insect. Beneficial insects help control tea scale – small parasitic wasps, convergent lady beetles, green lacewings and spiders. Preserve these natural enemies by using oil sprays instead of traditional insecticides and only spraying when absolutely necessary.
Heavy tea scales infestations may require 2 – 3 years for control. The bodies of the tea scale will usually remain on the plant after they die. Examine plants carefully after treatment to determine the level of control. Living tea scale will be moist when crushed while dead scale will be dry.
Source: University of Florida IFAS Extension and University of Georgia Center for Urban Agriculture, An Outreach of the UGA Center for Urban Agriculture – www.gaurbanag.org
Tea scale on the underside of camellia leaves. ©Theresa Friday, UF/IFAS.
Tea scale is a major camellia and holly pest in Florida.
Hard to detect and unimpressive-looking, scale insects are an underestimated danger to your landscape plants. Hiding under the “scale” covering (sometimes hard; sometimes fuzzy), these insects sit in one spot and suck plant juices—weakening or even killing the plant.
Tea scale appears as a fuzzy whitish coating on the bottom of leaves and causes yellow speckling on top. Heavily infested plants look unhealthy and produce little new growth. Other signs include leaf yellowing, dropping leaves, and branch dieback.
Tea scale is a difficult pest to control due to its habit of primarily infesting the underside of leaves. This makes spray coverage difficult. Additionally, it continuously reproduces in Florida’s warm climate.
A heavy infestation can debilitate the health of the plant because these scales are sucking the sap out of the plant. Infested plants have poor vigor, will not bloom well, and may eventually die.
Tea scale will usually not go away by itself. You can manage the tea scale problems in your landscape with horticultural oil products or choose a systemic product for season long protection.
Pruning beforehand can help, in that it opens up the dense foliage of camellias and hollies providing air circulation and better coverage of chemical sprays. Small non-flowering branches growing on major limbs within the interior of the plant should be pruned after flowering.
Oil sprays are effective in controlling tea scale and may be used in fall, winter, and spring when temperatures are mild (between 45-85°F). Be sure to thoroughly cover the underside of the leaf. You may have to repeat the application several several times. Follow the manufacturerʹs labeled rate for any product applied to control a pest.
Several tiny parasitic wasps provide some natural control, including Aphytis diaspidis and two species of Aspidiotiphagus; both have been reported parasitizing tea scale in Florida and Georgia.
Also on Gardening Solutions
- Camellia Pests and Problems
- Tea Scale, Fiorinia theae Green
Q: I have a camellia tree in front of my house in Savannah that is just gorgeous. But it’s dying!! A few months ago I noticed dense, very sticky webs strung along the low branches of the tree. The webs do not billow out, rather they’re very close to the branches, like a “web sweater” if you will. Inside of them are dark colored bugs.
Now, almost overnight it seems, a huge swath of the tree has lost its leaves and is dying. I cannot bear to lose this tree!
A: You have two insects present. First, barklice have covered the stems and bark with protective webbing. Barklice are harmless to the plant. They feed on debris found in the cracks and crevices of the bark.
A second insect is causing the massive leaf drop: tea scale. These sucking insects get their name from the fact that tea is made from one species of camellia. The scale insects attach themselves to the underside of leaves and suck cell juice, leading to a mottled appearance on the upper side.
The key to controlling tea scale is to spray the backside of all of your camellia leaves thoroughly with or . Spray the stems and trunk as well.
You may not be familiar with horticultural oil, though it has been used for decades. Just as the name says, it is a highly refined oil which has been tested for safety on plants. It works by suffocating the insects it coats. Years ago, the only time to use oil was during the late winter or early spring when the humidity is low. Otherwise the oil would harm plant leaves as well as the insects it was intended for. Over the last few years horticultural oils have become more pure, so they can be used in summer or winter.
See also Barklice
Tags For This Article: insects, Spring, Summer, Winter
Cottony Camellia Scale on Holly
The cottony camellia scale is most commonly reported on holly in Kentucky, but it is also found on other hosts, including yew, euonymous, maple, and hydrangea.
The cottony white egg sacs of this soft scale appear on undersides of leaves (Figure 1) in May and egg hatch (Figure 2) occurs during June. Crawlers settle on undersides of leaves and begin to feed on leaves during June. During this time they are susceptible to insecticidal soap; however, several applications may be needed due to an extended egg hatch.
Figure 1. Cottony camellia scale on holly (Photo: Brenda Kennedy, UK)
Figure 2. Eggs of cottony camellia scale just before hatching (Photo: Lee Townsend, UK
Managing Cottony Camellia Scale
Scale control is challenging and may require action over several seasons. Here are some points to consider:
- Proper timing of foliar sprays is a key to success. The spray must target newly hatched crawlers during June. Once settled on the plant, scale insects develop a protective covering that insecticides do not penetrate easily. The extended period of egg hatch may require two or more applications.
- Thorough spray coverage is essential. Depending on the type of insecticide used, control may be achieved by direct contact with the insects and/or picked up as they crawl over treated surfaces.
Many insecticides are labeled for control of scale infestations on trees and shrubs. Biorational choices include ultra-fine horticultural oils, insecticidal soap, and neem (azadirachtin). These insecticides will have minimal impact on beneficial species that help to regulate scale infestations, but they provide no residual protection. Conventional insecticides include those with one of the following active ingredients: bifenthrin, cyfluthrin, permethrin, or malathion. These products will provide residual control of active crawlers, but they have a significant impact on the lady beetles and tiny wasps that attack scales.
A dormant oil spray can be effective in controlling overwintering scales. Check the label for instructions and restrictions.
Scale infestations are often associated with stressed trees. Evaluate infested trees to identify and correct factors that may be contributing to stress. Prune heavily infested branches if practical.
By Lee Townsend, Extension Entomologist
Cottony Camellia Scale
Trees at Risk
Common hosts of the cottony camellia scale include: camellia, holly, yew, euonymous, maple, mulberry, hydrangea, rhododendron, and English ivy.
Signs of Damage
- Light green leaves.
- The insect is 1/8 inch long, oval, yellowish tan, with a brown margin.
- Forms cottony ovisac.
- Often on the underside of foliage.
- Sooty mold is often associated with CCS.
- Scales are cream to tan and elongate oval and relatively flat body.
- Young females have a dark stripe down the middle and mottling at the sides.
- Older scales are dark brown.
- Eggs are laid in an ovisac produced beneath and behind the female.
- Ovisacs are two or more times longer than the scales and are relatively flat, white, and fluffy.
- Cottony ovisacs are laid in May.
- Crawlers hatch in late May/June.
- Female insect overwinters as instars.
- Females mature in spring and lay eggs.
- One generation per year.
This is not an overly difficult insect to control. It is capable of laying up to 1,000 eggs at a time though, so monitoring is important. Large populations of scales are more difficult to control.
Other Treatment Practices
Maintain plant health and monitor closely for this insect.