A pest throughout most of the United States, black vine weevils (Otiorhynchus sulcatus) attack over 100 different kinds of ornamental plants including rhododendrons, azaleas, yews and hemlocks. When weevils enter your house, greenhouse or indoor gardens they can be damaging to begonias, ferns and other popular potted plants. They are particularly damaging to cyclamens and are often called the “cyclamen grub.”
- Life Cycle
- Vine Weevil Control
- How do I recognise a vine weevil?
- How do vine weevils affect the plants in my garden?
- How do I control vine weevils?
- JARS v57n4 – Practical Black Vine Weevil Management
- Garden pests – Vine Weevils
- What are vine weevils?
- How can I recognise vine weevil damage?
- What do vine weevils eat?
- How can I control vine weevils?
- Gardening Answers Knowledgebase
- Vine Weevil Killer Nematodes
- Nemasys Vine Weevil Killer
- Vine Weevil Killer Gel Nematodes
- Facts, Identification & Control
- What is a weevil?
- How do weevils eat?
- Common types of weevils
- How to get rid of weevils
- Ehrlich Pest Control gets rid of weevils
- How To: Get Rid of Weevils
Adult black vine weevils (3/4 inch long) are large slate-gray to black insects that cannot fly. They have short, broad snouts, bent or “elbowed” antennae and patches of short hairs on their wings. Adults feed at night, damaging plants as they chew small notches in the edges of leaves. During the day, they hide in soil cracks, garden debris and mulch.
Larvae cause the greatest level of injury to plants. They are small (1/2 inch long), white, C-shaped grubs that tunnel through roots as they feed. Leaves will often wilt (even when properly watered) and plants may be stunted or die. Larvae may also girdle the main stem just below the soil line.
Black vine weevils overwinter as nearly grown larvae in the soil around the roots of host plants. In spring they change to pupae and begin emerging as adults. In two or more weeks (depending on temperature) they begin depositing eggs near the crowns of the host plants. Hatching occurs in about 10 days, and the tiny larvae burrow into the soil and begin feeding. One generation per year.
Vine Weevil Control
- Remove mulch and other hiding places from around plants and water only when necessary (larvae and adults prefer moist soil).
- As non-flying insects, weevils travel from plant to plant by walking. It stands to reason then, that Tanglefoot Sticky Barrier should form the first line of defense.
- Apply 100% organic Diatomaceous Earth for long-lasting pest protection. Made up of tiny fossilized aquatic organisms, DE kills by scoring an insect’s outer layer as it crawls over the fine powder. Contains NO toxic poisons!
- Immature stages of the black vine weevil are particularly vulnerable to attack by beneficial nematodes, especially in potted plants.
- BotaniGard ES is a highly effective biological insecticide containing Beauveria bassiana, an entomopathogenic fungus that attacks a long-list of troublesome pests – even resistant strains! Weekly applications can prevent insect population explosions and provide protection equal to or better than conventional chemical pesticides.
- Fast-acting crack and crevice sprays, like Don’t Bug Me, can be used around windows, doors and vents to prevent adult weevils from entering structures.
- Least-toxic botanical insecticides should be used as a last resort. Derived from plants which have insecticidal properties, these natural pesticides have fewer harmful side effects than synthetic chemicals and break down more quickly in the environment.
Tip: Place burlap fabric at the bases of trees and shrubs to trap weevils that hide under it during the day.
The vine weevils is an insect that can cause serious damage to a wide range of ornamental plants and fruits, especially those grown in containers.
Very common in UK gardens and highly destructive, adult weevils eat plant leaves during spring and summer, but it is their grubs that cause the most damage. Feeding on the roots of plants during autumn and winter, an infestation often results in plant death.
Here’s everything you need to know about the pernicious little bug, and how you can prevent it from wreaking havoc in your garden.
How do I recognise a vine weevil?
Adult vine weevils are usually about 9-10mm long, with a black body with yellow flecks that looks pear-shaped when viewed from above. As they hide in the dark during the day, you’re more likely to spot them on your plants at night – they can’t fly, and are slow-moving crawlers.
All adult vine weevils are female and each can lay several hundred eggs during spring and summer. As they are even more damaging to plants, it’s very important to keep an eye out for vine weevil larvae, which are c-shaped, legless and white, up to a centimetre long, with pale brown heads.
How do vine weevils affect the plants in my garden?
Adult vine weevils bite notches into plant leaves and vegetation, which looks unpleasant but rarely affects plant growth. Far more serious is the damage caused by the soil-dwelling grubs; these will eat the roots of a wide range of plants, and can bore into tubers and stem bases. They will cause plants to wilt and die if left unchecked; most plant damage is caused from September to March as the grubs grow to adulthood.
Plants growing in pots and containers, outdoors or under cover, are most likely to be by vine weevil grubs – cacti, succulents, cyclamen, begonia and heuchera are particularly at risk. Plants growing in the open ground are less likely to be damaged, though it is best to check carefully.
How do I control vine weevils?
In spring and summer, the Royal Horticultural Society recommends inspecting plants and walls by torchlight and picking off adult weevils. They suggest shaking shrubs over newspaper to dislodge and collect more. They can also be trapped using sticky barriers placed around pots.
In sheds and greenhouses, look under the base or lip of pots and under benches; vine weevils also love to conceal themselves under debris, so pick up fallen leaves and sweep up in the greenhouse to reduce the number of hiding places.
Ornamental plants grown in containers can be treated by drenching their compost with dedicated weevil-killing insecticides, which are widely available. Use in mid-to-late summer will control larvae for up to four months. Remember, though, that these can’t be used to treat edible plants or ornamental plants growing in the ground.
If you don’t want to use chemicals, there are also biological weevil killers available that contain nematodes – microscopic creatures that are a natural enemy of vine weevils – which can be used in containers and in the open ground. These should be applied in August and early September, but they do work best in lighter soil, peat and compost.
It’s also important to keep checking your plants, even after using weevil killers; stopping control measures can allow vine weevils to reappear.
JARS v57n4 – Practical Black Vine Weevil Management
Practical Black Vine Weevil Management
Richard S. Cowles
Connecticut Agricultural Experiment Station, Valley Laboratory
Black vine weevil, Otiorhynchus sulcatus F, is the most obviously injurious insect pest of rhododendrons. Rhododendron enthusiasts are disheartened when purchasing precious species or hybrid plants, if they then find that the plant came with unwanted weevils “hitchhiking” in the roots. If the plant is small, feeding by black vine weevil larvae may cause sufficient root loss to kill the plant, or the larvae may girdle the main stem, with the same result. Larger plants can be affected in other ways. Root feeding can lead to nutrient deficiencies, because poorly functioning roots cannot translocate minerals available in the soil to the foliage. Finally, adult black weevils give plants a ragged appearance by notching the edges of leaves while feeding. This article is an update to my earlier review of black vine weevil biology (Cowles, 1995), and suggests practical approaches for managing this pest in nursery and landscape settings.
Figure 2. Adult weevil and notched damage on rhododendron leaf.
Photo by Hank Helm
Management in Container-grown Nurseries
Control of black vine weevils in nurseries is especially important, both for protecting plants and to prevent transport of this pest. During the early development of rhododendron plants, there is insufficient root tissue on an individual plant to support the development of black vine weevil larvae, leading to plant girdling (Cowles, 1995). I have observed long-term effects of partial girdling and root loss on the growth performance of nursery plants, so any early effort to prevent this feeding can be expected to yield large benefits in terms of improved plant growth.
During the last five years, dramatic advances have been made to control black vine weevil populations in container-grown nursery crops. Five years ago, the standard for disinfesting, or ridding, container-grown nursery plants of soil-dwelling insect larvae was a drench or dip with chlorpyrifos (Dursban), an organophosphate insecticide. Besides being relatively hazardous to humans and wildlife, chlorpyrifos was also quite toxic to the roots of the treated plants (Mannion et al. 2000). Because of these problems, several researchers, myself included, conducted screening trials to determine if other insecticides could replace chlorpyrifos to prevent or eliminate existing soil insect problems, including both white grubs (Japanese and oriental beetles) and black vine weevil larvae. The winner in these trials was bifenthrin (Talstar), a pyrethroid – the only insecticide providing complete control of both scarabs and root weevils (Cowles et al. 1997; Nielsen and Cowles 1998). Pyrethroid insecticides, which are used extensively in agriculture and the home, break down quickly when exposed to sunlight. However, my studies showed that when bifenthrin is incorporated into potting media, it is protected from sunlight and its half-life (the time for half of the chemical to disappear) appears to be between three and four years!
Further investigations on black vine weevil larvae demonstrated that low concentrations of bifenthrin permitted some larval survival among certain plants (e.g., Sedum and Astilbe). This incomplete control probably resulted from internal feeding of black vine weevils in roots, and an interaction between the nutritional quality of the roots, root weevil larval behavior, and the distribution and concentration of bifenthrin in the medium. If larvae find a dense growth of highly nutritious roots upon which to feed, they may become sedentary, thus limiting the likelihood that, through their movement, they would encounter lethal quantities of the insecticide (Cowles, 2001). Since rhododendron roots are of relatively low nutritional value for black vine weevils, and internal feeding is not possible for the larvae, either incorporation of bifenthrin granules or drenches of a flowable formulation through the potting medium can be expected to give near-quarantine level control of black vine weevil larvae in rhododendrons.
Another effective method for controlling black vine weevils in container-grown nursery stock includes the use of entomopathogenic nematodes (Cowles et al. 1997, Gill et al. 2001). These nematodes, or roundworms, are almost microscopic pathogens of insects. They search through moist soil for susceptible insects, enter into their body cavity, and release symbiotic bacteria, which quickly multiply and kill the host. Two or three generations later, the infective juvenile stage of nematodes emerges from the bacterial-soup remnants of the dead insect, to seek out new hosts.
Therefore, because they propagate in hosts, application of nematodes may lead to improved control of root weevil larvae over time. My studies indicate that black vine weevil larvae are susceptible to virtually any commercially available species, including Steinernema carpocapsae , S. feltiae , and Heterorhabditis bacteriophora (Cowles 1997).
The challenges for using entomo-pathogenic nematodes in the nursery setting are mostly due to their cost, and the fact that, since they are living organisms, they must not be subjected to extreme temperature conditions or stored for too long. Furthermore, they do not work well in preventive applications, because they need insect hosts in order to reproduce. Consequently, some degree of root injury would have to be tolerated if entomopathogenic nematodes are to be used as the principal management tool for root weevil larvae. However, if black vine weevil larvae ever develop resistance to bifenthrin, nematodes will become especially important in nurseries.
There is no excuse for nurseries to be shipping container-grown plants infested with black vine weevils, because very effective treatment options are now available. I suggest to retail nurseries receiving truckloads of plants that they inspect the insides of the shipping truck immediately after it is opened, so that the presence of adult weevils can be quickly detected. Since the inside of the unopened truck is dark, adult weevils wander out of their hiding places into the artificial “nocturnal” environment, and may be visible on the inside of the truck. If adults are present, then the recipient should inform the source nursery of the infestation. This can allow the source nursery to take corrective action in their plantings. Furthermore, the receiver needs to explore options and negotiate with the source nursery for determining who should pay for treatment costs when disinfesting the shipment.
The good news to rhododendron lovers is that methods available in nurseries for control of black vine weevils are environmentally superior, less toxic to humans, longer lasting and more effective than earlier organophosphate based chemical control. In fact, it is plausible that control of root weevils in the nursery with either bifenthrin or nematodes may provide continued benefit in protecting these plants after their installation in the landscape. With a long half-life, bifenthrin can be predicted to be present in the potting mix at insecticidal concentrations long after the initial application, and would be present around the crown of the plant where protection from larval feeding is most important. Insect pathogenic nematodes are quite hardy, and as long as some susceptible insects are present, these roundworms could become permanently established in the landscape along with the nursery plants.
| Figure 1. Many species of predatory ground beetles feed on any life stage of black vine weevils. Chlaenius tricolor is a striking exception
to the rule that carabid adults are drab black or brown colors. This carabid larva (unknown species) is also predatory.
Photos by Richard S. Cowles
Management in the Landscape
Black vine weevils, and in some parts of the country, other species of root weevils, are very common denizens of the woods and urban landscapes (Maier 1986, Helm, 2001). Because they are common in surrounding vegetation, and the adults are peripatetic (Maier 1978; 1986), even when uninfested rhododendrons are planted, it is not likely that they will remain weevil-free. One approach to keep plants free of weevils, or alternatively, to prevent feeding on foliage, is to exclude adults from the plants with barriers (Cowles 1995, Helm 2001). Pruning foliage so that it does not touch the ground or bridge to other surfaces, and placing an unclimbable barrier (plastic coated with Tanglefoot, grease, or Teflon) on the main stem can prevent adult feeding on foliage (Helm 2001). This method should be especially useful for obtaining show-quality trusses free of weevil feeding notches on leaves. However, this approach may not protect the root system, because weevils could still lay their eggs in the soil surrounding the stem. Another type of barrier can prevent weevils from gaining access to the foliage or the root system, by excluding adults further away from the plant. Bury aluminum flashing so that the edge projects about 5 cm or more above the surface of the soil and mulch, and then coat the top few cm of this aluminum barrier with lithium grease (the sort of grease used by auto mechanics). A grease band provides many weeks of protection, even under extreme rainfall conditions (Cowles 1997). A disadvantage of this approach is its ineffectiveness if weevils are already present on the plant or find some way of getting into the enclosure. At that point, the barrier would no longer provide much benefit.
For many years, one objective in landscape pest control has been to prevent adult feeding injury to foliage, usually by applying broad-spectrum insecticides to the leaves to kill the feeding adults. The strategy makes sense in several ways: adult weevils are the only stage that is exposed above ground, and the adult weevil requires about a month of intensive feeding before she is able to lay eggs. Therefore, spraying at monthly intervals should break the black vine weevil life cycle.
This adulticide (adult-killing) strategy is unfortunately flawed in two important ways. First, black vine weevil populations appear to be surprisingly adaptable, considering that they reproduce asexually. Various populations of black vine weevil adults that I’ve tested in my laboratory survived applications of acephate (Orthene), chlorpyrifos (Dursban), endosulfan (Thiodan) and carbaryl (Sevin). More importantly, I have observed populations of adult weevils in nursery and strawberry fields that survived any of the insecticides already mentioned, along with azinphos- methyl (Guthion), bendiocarb (Turcam), fenpropathrin (Tame), and bifenthrin (Talstar). Putting it simply, some black vine weevils have apparently become resistant to any of the organophosphate, carbamate, or pyrethroid insecticides used for their control. Therefore, it is possible that the insecticides sprayed to kill the adult weevils in the landscape won’t work.
A second reason that the adulticide strategy can be counterproductive is as follows: a wide variety of predatory ground beetles (carabids), both the adults and larvae, continuously cruise through leaf litter, the soil surface, and the soil in search of various insects to eat. These beneficial insects are probably more susceptible to the insecticides than are the weevils. Thus, if an insecticide-resistant weevil population is sprayed, the only result may be to chemically protect the weevils from their predators! The consequences of these dynamics can be extraordinary. In one field-grown yew nursery, where insecticides had been intensively used, I found (in a pitfall trap survey), approximately 1,500 black vine weevils and 200 predatory ground beetles. At the same time, in an unsprayed nursery, and with the same trapping effort, I recovered three black vine weevil adults and 950 predators. There were so few black vine weevils at this second site that the grower didn’t even know that the pest was present. I have trapped about fifty-five species of these predators in commercial yew nurseries, ranging in size from 3 to 24 mm long. Depending on their size, carabids may be capable of eating weevil eggs and young larvae, or with the largest species, even be capable of eating several weevil adults.
To check on the relative abundance of carabids and black vine weevils, bury a 16 fluid ounce plastic cup up to the rim into the soil under or next to your rhododendron shrub. Coat the inside top inch of the cup with motor oil to make an unclimbable surface, and check the contents of this pitfall trap every few days. Neither carabids nor black vine weevil adults fly as adults, so any beetles that stumble in will be unable to climb back out.
Based on field observations, I can suggest that management of black vine weevils in the landscape should principally be based on biological control. If there is much weevil feeding on foliage, then efforts to establish insect pathogenic nematodes in the soil are probably warranted. If you do apply nematodes, irrigate the soil beforehand, check with a hand lens to make sure that the commercially-grown nematodes are alive and wiggling, and keep the soil moist with intermittent watering for a few weeks following application. May or late-August application timing appears to be appropriate for targeting weevil larvae (Cowles 1997). Since root weevils develop very well on many other kinds of plant materials (such as arborvitae, spruce, hydrangeas, ferns, and many broad-leaved perennials), take care to apply nematodes to reduce the numbers of larvae feeding on these plants, too. Nematodes reproduce best in an environment with a high population of hosts, so expect the best results where there is the greatest concentration of root weevil larvae.
While some researchers have thought northern soils are too cold for entomopathogenic nematodes to succeed, or even survive (Rutherford et al. 1987, Helm 2001), my field surveys in Connecticut, and additional surveys in New York, Oregon, and the Canadian Rockies have demonstrated the natural occurrence of these nematodes (Fergusen et al. 1995, Liu and Berry 1995, Mracek and Webster 1993). The only way that these nematodes could be present at these sites would have been for them to successfully infect and reproduce in hosts, and to survive from one year to the next. Finding native populations of nematodes at these sites proves that insect pathogenic nematodes can survive in northern and cold climates, but does not guarantee that these natural populations will be effective in suppressing root weevil populations. One interpretation of black vine weevil’s life cycle is that egg-laying as late as September (my observations), and the ability of larvae to develop at temperatures below 11°C (Stenseth 1978), may be adaptations that permit larvae to develop at times of the year when soil temperatures are too cold for insect pathogenic nematodes to reproduce. Therefore, applying nematodes may still be necessary to provide sufficient numbers of nematodes in the brief periods of time when larvae or pupae are present and soil temperatures are warm enough for an infection cycle to take place. Based on field survey data, if susceptible hosts are present, these nematodes can become permanently established following their application.
Because many predatory ground beetles are generalists, eating virtually anything that moves and is small enough for them to consume, their continued existence in a landscape is independent of the presence of root weevils. When they don’t have weevils to eat, they can sustain themselves by feeding on various other insects that live in the soil, mulch, and leaf litter. Therefore, they can outnumber root weevils and keep them at low populations. It is known that cultivation, insecticides, and some slug and snail baits adversely affect carabids (Cilgi et al. 1996), so avoiding excessive hoeing and these products may help to conserve the predators. Manipulating the habitat to encourage these predators could also be beneficial. They do well in environments protected from the sun, so coarse mulch should increase their activity (Wilson et al. 1999). The gradual decomposition of mulch should provide many additional benefits to rhododendrons (weed control, conservation of water, and additional organic matter), and can serve as the food for detritivores (small insects and earthworms) essential, in turn, for feeding carabids.
My past twelve years of work on black vine weevils, generously supported by the American Rhododendron Society, have caused me to have a tremendous respect for this insect. While the adulticide approach theoretically should give good control of this pest, insecticides have not yet been found that can selectively kill weevil adults rather than beneficial predators. Part of this challenge is the superior ability that weevils have for coping with poisons, which is probably a preadaptation evolved from feeding on the foliage of what, to us, are highly toxic plants (e.g., rhododendrons and yews). To be appropriate for use in the landscape, an insecticide useful for killing black vine weevil adults must either take advantage of internal physiological differences between black vine weevils and predatory ground beetles, or would have to specifically be toxic to weevils only through ingestion. Although carabids won’t eat rhododendron leaves, they are sufficiently omnivorous to be poisoned by apple fiber-based insecticidal weevil baits (Cowles 1996).
Overall, taking advantage of the black vine weevil’s natural enemies – entomopathogenic nematodes and predatory ground beetles, probably has the best chance for protecting rhododendrons from serious root injury. To accept this strategy, rhododendron fanciers will have to accept a certain amount of leaf notching. Permitting a few weevils to feed on the foliage should not jeopardize the health of established plants, and a small amount of weevil feeding is a sign that the landscape has a healthy, multi-layered ecosystem, complete with prey and predators.
Garden pests – Vine Weevils
Vine weevils are hated by UK gardeners
Image: Jiri Prochazka
Vine weevils are known and loathed by gardeners around the country for their two-pronged attacks on both the foliage and the roots of a huge variety of plants, especially those in containers. Read on to find out how to control this garden pest.
What are vine weevils?
Vine weevils are destructive garden beetles that feed on plants during both stages of their life cycles. The adult weevils are active from spring to late summer, while the grubs feed from autumn to early spring.
The adults are black in colour with a yellow mark on their wings. They are usually around 9mm in length and the females can lay hundreds of eggs during the season. The grubs, meanwhile, are pale in colour with slightly brown heads and around 1cm in length.
How can I recognise vine weevil damage?
Irregular notches on leaves are signs of vine weevil damage
Adult vine weevils leave distinctive bite marks on foliage, with irregular-shaped notches along the leaf margins. These are particularly visible during the summer months while the adults are active.
However, the plants can usually withstand damage caused by the adult vine weevils. It’s unsightly, but it doesn’t usually result in plants losing vigour. It’s the grubs, which live underground and eat the roots, corns, and tubers, that cause more serious damage, including plant death.
What do vine weevils eat?
The leaves of this rhododendron bush has clear signs of vine weevil damage
Image: Kazakov Maksim
Vine weevils eat a wide variety of fruits and ornamental plants, both indoors and outdoors, but they are particularly drawn to those grown in containers and those with succulent stems and leaves. In fact, there are few plants that are completely resistant to vine weevils.
Herbaceous plants and shrubs – such as rhododendrons, hydrangeas, evergreen euonymus, and bergenia – are also particularly attractive to the adult beetles, which feed on the foliage.
Even though plants in open ground are slightly less likely to be attacked by this pest, you may nevertheless still encounter infestations, especially for plants like strawberries, young yew plants, primula, polyanthus, and more.
How can I control vine weevils?
The grubs of vine weevils live in the roots of plants
Image: AHDB Horticulture TV
Vine weevils are destructive, but there are several measures you can take to control their numbers and limit their impact on your garden. But whichever solution you choose, you’ll need to stay vigilant to make sure that their numbers don’t have a chance to recover.
- • Remove the adult weevils – regularly check the plant (as well as the surrounding area, like under pots) for the beetles and remove them from the plant either by hand or by gently shaking the plant over newspaper. You can also trap them around the pots using special sticky traps.
- • Remove the grubs – the grubs are usually found around the plant roots, which aren’t easily accessible, but compost can also be infested. Remove as many as you can.
- • Limit their food supply – discourage vine weevils from your garden by growing plants that they are less attracted to. Plants with fragrant leaves – such as Lavender, Lemon Balm, Geranium macrorrhizum, and Mint – appear to be less vulnerable to attack from the adult weevils. They also seem less attracted to furry leaves, such as those of Stachys byzantina.
- • Weed regularly – adult larvae love certain types of weeds, such as willow weed, so keeping on top of the weeding may help limit their numbers.
- • Encourage natural predators – the natural world can help you keep vine weevil numbers down, with creatures like frogs, hedgehogs, and birds preying on beetles. Create a hospitable environment for these beetle predators by providing food and water.
- • Use biological controls – nematodes are effective in killing the larvae in the soil, both in beds and containers, during the warmer months when the soil is at least 5°C.
- • Apply a liquid drench to the compost – this kind of pesticide can be applied to compost in containers and will control the larvae. For best results, use it in mid- to late summer so the effects last well into the autumn and spring when the larvae are at their most destructive.
Which plants do vine weevils not like?
Plants with fragrant leaves seem to be less frequently attacked by adult weevils. Plant Lavender, Lemon Balm, Geranium macrorrhizum, and Mint. They also seem less attracted to furry leaves such as those of Stachys byzantina.
Gardening Answers Knowledgebase
Search Results for: Root weevils | Search the catalog for: Root weevils
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Plant Answer Line Question
I have a line of Ward’s ruby azaleas. The three weakest ones have a lot of tiny notches in the leaves. I seem to remember the notches from the root weevil as being larger than these. Are the tiny notches from something else?
I also noticed that some of my dahlias have splotched leaves and that when I disturb the leaves, white-looking insects fly off the leaves. These flies apparently have spread to tomatoes as well. Are these whitefly? Will they disappear after the winter or is there some control I should use to prevent them from taking over?
First you need to get an accurate diagnosis of your problems. If you are in King County, you can bring samples to a Master Gardener Clinic. For information about Clinic hours see their website (Plant Clinic Schedule).
Oregon State University offers this information about root weevils and Rhododendron (which includes Azaleas). It describes using beneficial nematodes as a control.
According to Washington State University Cooperative Extension’s publication, How to Identify Rhododendron and Azalea Problems (1984), root weevil damage to foliage is not usually a serious problem. You can check for weevils with a flashlight at night to confirm that they are the source of the notches you are seeing. There are some Neem oil-based products that may be helpful, but they must be used at the correct times of year. See WSU’s HortSense page.
As for the dahlias and tomatoes, it is important to determine exactly what the insects are before proceeding with treatment. If they are whiteflies, you can put yellow sticky traps around the plants to trap them. University of California, Davis’s Integrated Pest Management site has other recommended control methods, including reflective mulch. You may not want to use insecticidal soap:
“Insecticides have only a limited effect on whiteflies. Most kill only those whiteflies that come in direct contact with them. For particularly troublesome situations, try insecticidal soap or an insecticidal oil such as neem oil or narrow-range oil. Because these products only kill whitefly nymphs that are directly sprayed, plants must be thoroughly covered with the spray solution. Be sure to cover undersides of all infested leaves; usually these are the lowest leaves and the most difficult to reach. Use soaps when plants are not drought-stressed and when temperatures are under 80 degrees F to prevent possible damage to plants. Avoid using other pesticides to control whiteflies; not only do most of them kill natural enemies, whiteflies quickly build up resistance to them, and most are not very effective in garden situations.”
Keywords: Root weevils, Rhododendrons–Diseases and pests, Gaultheria shallon
Last year I had a big problem with weevils in my salal, rhododendrons and a few other shrubs. I am not sure if they returned after putting down beneficial nematodes last fall.
Weevils are tough! You are on the right track with beneficial nematodes. It might take a few seasons to make a difference. Here is a link to information by entomologist Art Antonelli of Washington State University about controlling weevils, especially on Rhododendron. Here is another article from Thurston County Hazardous Waste.
Keywords: Root weevils, Rhododendrons–Varieties, Rhododendrons–Diseases and pests
My rhodies are being devastated by root weevils. They have stripped many of the branches clean of their vegetation, and have destroyed ~50% of the remaining leaves. My rhodies look like they will require years to recover, if they ever do.
If I replace them with resistant varieties or plants that are not susceptible to these pests, will this eliminate the weevils?
Root weevils are the most common pest attacking Rhododendrons in the Pacific Northwest so they can only be temporarily eliminated from any garden. If the environment is right and their food source returns, so will the root weevils.
If you want to keep your current Rhododendrons, the weevils can be controlled if you’re diligent (forever!?). An article by Caroline Cox in the summer 2005 issue of the Journal of Pesticide Reform discusses their control. However, it sounds as if you’re willing to remove them and start fresh. Some of the most susceptible (host plants) are Rhododendron and Azalea, Heather, Salal, Manzanita and Kinnikinnick, Pieris, Maples, Viburnum, most Conifers, Astilbe, Cyclamen, Helleborus, Hosta and Primrose.
(Source: Root Weevils in the Nursery and Landscape; Identification and Control, by J. DeAngelis and G. Garth, EC 1485, Oregon State University Extension Service).
The extension bulletin from the Washington State University Extension website has an excellent list of resistant Rhododendron varieties.
Keywords: Insect pests–Control, Root weevils, Heuchera, Bergenia
What is the pest that eats little notches around my Bergenia and Heuchera? What can I do to prevent this?
It is possible your Bergenia and Heuchera are being nibbled by black vine weevils or strawberry root weevils. Usually you would begin to notice the damage in mid-spring. The notches won’t kill your plants, but if you have a lot of black vine weevils and plants appear to be wilting, you may want to attempt to control the larvae. Spraying beneficial nematodes (Steinernema) on the surrounding soil may also help.
Below are links to information about weevils:
Black Vine Weevil from UMass Extension
Black Vine Weevils from University of California’s Integrated Pest Management site
Strawberry Root Weevil from the Pacific Northwest Insect Management Handbook
A document about Black Vine Weevil (and other root weevils) from Ohio State University Extension
“Adults that feed along leaf margins produce typical crescent shaped notches. Careful searches should be made to try and locate specimens since several other weevils and some caterpillars can produce this same type of notching. Moderate to light notching seems to have little effect on plant health.
“Black vine weevils are oblong oval in shape, about 1/2-inch long and have a short, broad snout with elbowed antennae. The body is slate grey to blackish brown and the wing covers have numerous small pits and short hairs. This pest is difficult to distinguish from other Otiorhynchus weevils. The strawberry root weevil is usually half the size of the black vine weevil, and more brown in color. The rough strawberry root weevil is only slightly smaller than the black vine weevil but the collar just behind the head, the pronotum, is heavily pitted.
“Female weevils emerge from soil pupation chambers late May to early July. These weevils must feed on plant material for 21 to 45 days before they are ready to lay eggs. After the preoviposition period has passed, the females place several eggs each day into the soil or leaf litter nearby suitable host plants. The weevils hide during the daytime at the base of plants or in mulch and leaf litter near food plants. Adults may live 90 to 100 days and usually lay 200 eggs during this time. The eggs hatch in two to three weeks and the small C-shaped, legless larvae feed on plant rootlets. The larvae grow slowly over the summer, molting five to six times. By late fall the larvae have matured and are about 5/8-inch long. The mature larvae enter a quiescent prepupal stage in an earthen cell and pupate the following spring. A single generation occurs each year.
“Strategy 1: Habitat Modification – Egg and larval survival is helped when soil moisture is moderate to high in July and August. Heavy mulches also help maintain critical moisture levels. Remove excessive mulch layers and do not water plants unless necessary. Excessively damp soils in the fall also force larvae to move up the base of the plant where girdling can occur. Properly maintain rain down spouts and provide for adequate drainage of soil around plants.
“Strategy 2: Biological Control Using Parasitic Nematodes – The entomopathogenic nematodes, Steinernema and Heterorhabditis spp., have been effective for controlling black vine weevil larvae, especially in potted plants. Sufficient water must be used during application to wash the infective nematodes into the soil and root zone. If the nematodes are to be used in landscape plantings, remove a much of the mulch as possible and thoroughly wet the remaining thatch and soil before and after the nematode application. Applications of the nematodes in landscapes has produced variable results.”
Keywords: Root weevils, Primula
I have grown primroses both in Seattle and in South Everett. The first time the plants looked like the leaves were being eaten, and then when I pulled one of the almost-eaten plants out of the pot, most of the roots were gone. When I cleaned out the pot, I found many little white grubs in the dirt. It happened again in my new location. I am mystified, as I grow them in pots on a second floor balcony. What could be causing this and is there a way to grow primroses without this happening?
I wonder if the problem is in the potting soil. Were you using the same batch each time? It might be worth experimenting with a new brand of potting soil to see if you have the same or different results.
Also, you could try purchasing your plants from different sources. The ones you have now may have come to you from the nursery already infested.
There are a number of pests that afflict Primula. Of the culprits listed on University of California, Davis’s Integrated Pest Management site, weevils might be a possibility, as their larvae (grubs) live in the soil. The recommended treatments include parasitic nematodes and trapping of adult weevils. Here is more on this pest, from the Connecticut Agricultural Experiment Station.
Keywords: Insect pests–Control, Root weevils, Slugs
A trip through the garden at night with a flashlight will reveal a surprising amount of animal and insect activity. Earthworms crawl across the ground looking for decomposing plants to consume while weevils, slugs and cutworms feed on our prized shrubs and perennials. Remember that the new non-toxic iron phosphate slug baits, such as Sluggo, must be reapplied about every two weeks. More slug-coping advice can be found online at www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7427.html
The life cycle of the black vine weevil consists of an egg, 6 or 7 larval instars, a pupal instar and the adult beetle. In temperate climates in the Northern hemisphere, the first adult weevils appear around May. They are approximately 7 – 10 mm long, brownish black and have dull yellow spots on their back. The wing covers are grooved and fused with the body. Therefore, vine weevils cannot fly but can walk very well. They are strictly nocturnal; during the day they hide, and can often be found between the inside of a plant pot and its contents, under lumps of e, in vegetation and under planks etc.
In temperate climates, the small (0.7 mm diameter), spherical white eggs are laid from the beginning of July until around the end of October. The larvae that hatch have a white, translucent to pinkish body and a reddish brown head. These larvae live in the root zone in the soil where they feed on the roots. They are legless, roughly 1 mm long at hatching, but grow to approximately 12 mm. A larva is often curled into the typical C-shape which it assumes whenever it is disturbed. The body is covered with stiff white to light brown, bent hairs. Overwintering occurs in the larval stage, usually as medium sized instars. Once the temperature rises, the larvae become active again. The full-grown larvae pupate in spring in the soil. The depth where the pupae can be found varies between 2 and 20 cm. Pupae are white to cream coloured and 7 – 10 mm long. Outdoors there is a single generation each year. A population of black vine weevils consists entirely of females and reproduction is by parthenogenesis.
As vine weevils cannot fly their dispersal ability is limited compared to many other insects. Spread over longer distances usually occurs with infested plant material. Because Otiorhynchus sulcatus is parthenogenetic a single female is enough to start a new population.
Vine Weevil Killer Nematodes
Nemasys Vine Weevil Killer is the simple solution to control vine weevil and is available in pack sizes of 12 sq.m/14 sq.yds (treats approx 210 7.5 litre pots) or 100 sq.m/125 sq.yds (treats approx 1700 7.5 litre pots).
To keep a minor problem at bay, one autumn treatment should be adequate. However, for a serious infestation, treat in the spring and again in the autumn. When treating pots take care that soil is not left to dry out.
The nematodes (Steinernema kraussei), seek out the vine weevil larvae and attack the pest by entering natural body openings. Once inside, they release bacteria that causes blood poisoning stopping the larvae from feeding, quickly killing it. The nematodes then reproduce inside the dead pest and release a new generation of hungry infective nematodes, which disperse and search for further prey. Nemasys Vine Weevil Killer will kill larvae present in the area and protect against further larvae damage for up to four weeks.
What is Nemasys Vine Weevil Killer? Nemasys Vine Weevil Killer is a natural product containing microscopic worms (nematodes) which seek out and kill vine weevil larvae.
Why use Nemasys Vine Weevil Killer? Nemasys Vine Weevil Killer is an effective alternative to chemicals and is harmless to children, pets, birds and wildlife. It is also suitable for use on edible crops and open ground where it is not permitted to use chemical controls.
How should I apply Nemasys Vine Weevil Killer? Nemasys Vine Weevil Killer is simple to apply, you just need a watering can and water. When applying to pots make sure that not too much water flows out of the drainage holes so the nematodes are not lost.
When can I apply Nemasys Vine Weevil Killer? Nemasys Vine Weevil Killer should be applied when the soil temperature is above 5oC (41oF) and the vine weevil larvae are present. Outdoors this is usually March to November, undercover vine weevil can be controlled year round. Nemasys Vine Weevil Killer kills vine weevil larvae and not the adult beetles.
Where should I apply Nemasys Vine Weevil Killer? On to the soil or compost that is infested with the larvae.
Are any special conditions required? Nemasys Vine Weevil Killer should be applied to moist soil. If applying in hot weather it is better to wait till later in the day when the soil won’t dry out quickly, so the nematodes will have a chance to migrate under the ground during the night.
How often do I need to apply Nemasys Vine Weevil Killer? Vine weevils are widely distributed across the United Kingdom living in gardens and hedgerows. Therefore it is difficult to completely eradicate the pest since adults may reinvade from outside your garden. If you have what you think is a serious infestation you should consider treating twice a year, in spring and autumn. If you are less concerned and just want to keep a minor problem at bay then one treatment should be adequate.
What do vine weevil eggs look like? Vine weevil eggs are white when laid, approximately 0.8mm in diameter and round. They rapidly turn brown as they mature. The eggs are often confused with slow release fertilizer pellets, however the pellets are much larger, 2mm in diameter.
What can I do to control the adult vine weevil? Finding and destroying the adults is difficult, so it is better to use nematodes to kill the larvae and break the lifecycle.
How much damage is caused to plants by the circular notches that the adult vine weevils make around the leaves? The circular notches, whilst unsightly, are unlikely to kill the plants. However, they are a timely reminder that there is a vine weevil problem that will need to be dealt with at the larval stage.
Can I water Nemasys Vine Weevil Killer directly on to plants? Nematodes live in the soil so, if you can, it is better to apply to the soil. However, if because of dense foliage this is impossible, after application wash them off into the soil with some extra water.
Nemasys Vine Weevil Killer
What is a vine weevil and how do they live (lifecycle)?:
- Vine weevils are beetles. They have a long thin snout and are approximately 8-14 mm (¼ to ½ inch) in length. They are dull black with patches of tiny yellow bristles. They cannot fly but can walk 3 miles in a year.
- All adults are female and lay hundreds of white eggs, approximately 0.8 mm in diameter and round. They rapidly turn brown as they mature.
- The eggs are often confused with slow release fertiliser pellets, such as, Osmocote, which are found in most common compost mixes. The Osmocote pellets are 2 mm in diameter, release liquid fertiliser when squashed and range in colour from yellow to dark brown.
- The eggs hatch in to larvae that are ‘C’ shaped and legless, with a small head. The larvae feed and grow throughout late summer and autumn. During winter their growth slows as temperatures decrease and feeding activity also decreases. As the temperature rises in spring, larvae activity starts to increase again causing more and more root damage.
- Eventually the larvae stop feeding and pupate (during May) and quickly hatch into adults, and so the cycle continues.
- Outdoors, the adults emerge in early summer (June) and lay their eggs immediately, starting the year long life cycle again.
- Indoors, vine weevil will breed all year round resulting in the pest being present at all stages at any one time.
What damage does a vine weevil do and how do I recognise it?:
- The adults eat plants in summer and autumn, leaving distinctive crescent-shaped notches on leaves. Finding and destroying the adults is difficult as they are nocturnal, quick moving and play dead once disturbed.
- The vine weevil grub (larvae) is far more of a danger to plants than the adults. The young larvae feed on plant root systems, initially on small fine outer roots, but progressively attacking the more important main roots as they grow bigger.
- The first signs of attack by the larvae are usually when the plant starts to wilt. This is too late to save it! It is therefore more important to kill the larvae than the adults.
- Primulas, fuchsias, begonias, most evergreen plants and all plants in pots are particularly at risk. They also attack strawberry and raspberry plants.
Nemasys Vine Weevil Killer: – environmentally friendly and safe for children, pets and wildlife
- Nemasys Vine Weevil Killer is the simple solution to control vine weevil.
- Apply to pots and open ground from March to November. This is when the vine weevil larvae are present and the soil is above 5ºC (40ºF). If applying under cover the pest’s lifecycle is broken and Nemasys Vine Weevil Killer can be applied at any time, as long as the soil is above 5ºC (40ºF). Apply directly to the soil around the roots, which is where the larvae will be feeding.
- To keep a minor problem at bay, one autumn treatment should be adequate. However, for a serious infestation, treat in the spring and again in the autumn. When treating pots take care that the pots are not allowed to dry out.
- The nematodes (Steinernema kraussei), seek out the vine weevil larvae and attack the pest by entering natural body openings. Once inside, they release bacteria that stops the larvae from feeding, quickly killing it. They do not stop there. The nematodes reproduce inside the dead pest and release a new generation of hungry infective nematodes, which disperse and search for further prey. Nemasys Vine Weevil Killer will kill larvae present in the area and protect against further larvae damage for up to four weeks.
- Nemasys Vine Weevil Killer is available in pack sizes:
- 12 sq.m/14 sq.yds – (160 Pots)
- 100 sq.m/125 sq.yds – (1333 Pots)
How to apply the nematodes:
Once mixed with water, apply immediately, making sure they are applied to the soil. Wash any nematodes off the leaves using more water.
It is important to water the lawn thoroughly immediately after applying Nemasys Chafer Grub Killer and Nemasys Leatherjacket Killer. This is to ensure the nematodes reach the soil where the target pest is located. Make sure the lawn does not dry out after applying nematodes.
Watering can method:
- Open, take a portion of the pack and put in a watering can
- Add water and stir
- Water on soil/lawn and then water in with hose/watering can
Vine Weevil Killer Gel Nematodes
Vine weevil larvae can be controlled with nematodes that infect and kill vine weevil larvae. Supplied as low temperature Steinernema species nematodes for spring and autumn application and Heterohabditis species for late summer.
Vine weevil is one of the most destructive gardens pests. Adults are nocturnal and can travel quite long distances. Once they have laid eggs, these quickly turn into vine weevil larvae, which feed on plant roots. The larvae are especially destructive and damaging to a wide range of plants. After infection by nematodes the larvae turn dark brown and disintegrate. In cooler conditions in the spring and late autumn; Vine Weevil Killer contains a nematode that is active at lower soil or compost temperatures and then in the summer months it is supplied with a nematode suited to higher temperatures.
These tiny microscopic nematodes are watered into pots and containers. They can also be used on raised beds, flower beds and borders. Vine weevil larvae are normally present in gardens in the spring and late summer. Dragonfli now supplies its larger packs of Vine Weevil Killer in a new gel formulation that increases the shelf life of the nematodes and we can provide programmes of Vine Weevil Killer introductions that help you apply the nematodes at the time of year they are most likely to be effective.
Vine weevil killer nematodes can be applied with a watering can or knapsack sprayer. For the best results ensure the compost/soil is moist prior to application and for some days afterwards. This will help the nematodes enter the compost to search and find the Vine weevil larvae. Avoid applying in bright conditions due to the nematodes being UV sensitive. Apply the nematodes as soon as possible after receipt or store in a fridge unopened. Gel packs can be stored for 10 weeks and non-gel 4 weeks.
Delivery Note; Same day dispatch Mon-Fri before 2pm
Facts, Identification & Control
What Are Weevils?
Weevils are actually beetles. There are more species in this family than in any other beetle group. Scientists estimate that there are over 1,000 species of Curculionidae in North America.
What Do They Look Like?
Weevil species occur in a wide range of colors and body shapes:
- Size: Many are slender or oval-shaped insects. Depending on the species, weevils range in size from about 3 mm to over 10 mm in length.
- Color: They are usually dark-colored (brownish to black).
- Head: The most distinctive feature of weevils is the shape of their head. An adult weevil has an elongated head that forms a snout. The mouth is at the end of the snout. Some weevils have a snout that is as long as the body. Another family of beetles called Bruchidae, such as the cowpea weevil, have a different appearance from the typical weevil. They lack the elongated snout found in the Curculionidae.
How Did I Get Weevils?
While weevils can find their way into a home from the yard, these pests usually come indoors inside packaged foods or bulk products. Weevil eggs are almost invisible to the naked eye, so it’s easy to buy tainted goods without realizing those goods are infested. Weevils usually infest grains and starches like rice, flour, pasta, and cereals.
Weevil infestations that start outside may be the result of fruit trees or gardens, which are also food sources. The insects often gather on the sides of homes and move into cracks and gaps that lead inside.
How Serious Are Weevils?
Outdoors, weevils can kill garden plants. Indoors, the pests are more of a nuisance than a danger. Weevils contaminate infested food with their feces and cast skins, causing more damage than they eat. So, an infestation may render entire packages or pantries of food inedible. Stored product weevils do not bite and they do not cause damage to dry, decay-free wood inside homes.
Stored Product Weevils
A few weevils attack stored grains and seeds. They can be very destructive, and their damage is often very expensive. The most common stored product weevils are:
- Cowpea weevils, Callosobruchus maculatus (F.)
- Granary weevils, Sitophilus granarius (L.)
- Rice weevils, Sitophilus oryzae (L.)
Some weevils can become structural pests. These are the weevils that upset homeowners because they invade homes often in great numbers. Some of them invade in the fall. They hide during the winter and leave in the spring. Others invade in the summer when the weather starts turning hot.
Signs of Infestation
Homeowners might not notice weevils when they are gathered on the outside of the home. But if the weevils manage to find an opening and invade the home, the homeowner often finds hundreds of insects crawling on the walls and windowsills.
How Do I Get Rid of Weevils?
What You Can Do
Most likely, homeowners seeing weevils are dealing with the stored product species. The most important control methods are to find the infested material and eliminate it. Careful inspection of items before purchasing can help prevent getting a new infestation. Products with holes or signs of damage on the packaging should not be purchased.
A vacuum cleaner is a quick way to remove weevils from the walls and furniture. Be sure to take the vacuum outside to empty it so the weevils don’t reinfest the home.
What Orkin Does
The Orkin Man™ can help homeowners manage weevils. He will use Orkin’s exclusive A.I.M. system—Assess, Implement and Monitor. He will design a treatment plan for your home’s situation. By focusing on the source of the problem—outside or inside of the home—he will be able to help keep weevils from invading again.
When weevils invade, they can come in large numbers. Homeowners often feel more confident calling the local Orkin branch office to get The Orkin Man™ to help get weevils out of their home and keep them out.
If weevils haven’t invaded, there is time for some prevention. Check outside for any openings that weevils could use to get inside. Look around doors and windows for missing caulk and damaged weather stripping. Check attic vents and crawl space vents for torn screens.
Biology, Diet, & Habits
What Do They Eat?
Weevils feed on plants in the larval stage and as adults. Some can be very destructive to crops. For many years, one of the most destructive weevils was the cotton boll weevil. The black vine weevil, Otiorhychus sulcatus (F.), is found in many parts of the United States. It feeds on a variety of plants, including hemlocks and rhododendrons.
Where Do They Live?
Most weevils are found in
Weevil life cycles depend greatly on the species. For some, in spring, adults lay their eggs on the ground near host plants. When the eggs hatch, the larvae burrow into the ground and feed on the roots. Since the larvae are underground, people seldom see them.
Many of the larvae spend the winter in the ground and emerge as adults the following spring. However, the adults that emerge during the summer or fall may invade homes for shelter. Some, like the Asiatic oak weevil, are attracted to light, so they are drawn to homes at night. Others may be attracted by the warmth from the house.
Types of Weevils
More facts about weevils:
Around the world, when it comes to pests that can ruin entire shipments of food or fields of crops, one of the most common pests is the simple weevil. For an insect so small, it is amazing just how fast weevils can infest a commercial food processing or food handling business. Likewise, weevils can cause a lot of damage to commercial farms by infesting crops like wheat and grains.
Because weevils are so small (most of them are less than 6mm in length), they can sometimes be hard to see. Weevils are also very specialized, often attacking one kind of crop or food product only. Farmers and business owners often may not realize they have a weevil infestation until the food starts going bad, or the crops start to die off. This makes food products unsalable and can cost businesses tremendous financial loss.
Ehrlich Pest Control is the expert in taking care of businesses in the food processing and handling industries. We can provide treatments that will get rid of weevils and offer services to prevent weevils from coming back. If you think your business might be at risk for weevils, contact your local Ehrlich office today.
What is a weevil?
There are many species of weevil around the world. All of them are a type of beetle and part of the Curculionoidea superfamily. Almost all of them are herbivorous, which means they love to eat plants. There are reportedly more than 60,000 species of weevil, but there is only a percentage of them who are “true” weevils. Some other species of beetle have been given the name, but they are not actually weevils.
The vast majority of weevil species burrow into the stalks or portions of plants and will eat them from the inside. Most weevils prefer to be in nature and eat plants (including crops), it is very easy for businesses which store rice or wheat/flour to end up with weevils inside them.
How do weevils eat?
Weevils have specialized mouthparts. The typical weevil has a long “snout” which allows them to pierce the stalks and grains. Some weevils are so small, they can even burrow into a single grain of rice to eat it from the inside out. Once weevils have eaten away the insides of the plant they are feasting upon, the plant usually dies.
Rice weevils, grain weevils, wheat weevils and other species can be found in-store food products. Weevils can infest entire supplies of wheat, grains, or rice. They are also common in stores of pasta and other food substances made from wheat. This is why weevils can be a real problem for food storage and food processing businesses.
Common types of weevils
Some regions of the U.S. have more weevil activity than the rest of the country, including most of the northeastern states. This includes states like Maine, which seems to be a haven for weevils. Some of the most common types of weevils found in businesses there include:
This type of weevil has a very long snout which it uses to pierce the skin of various types of fruit. The weevils dig channels into the fruit and then lay eggs inside of them. The initial piercing of the fruit is enough for them to go bad, but once the eggs hatch, the fruit is completely ruined.
Oak timberworm weevil
These beetles are also black in color and elongated a bit. They have gold flecks on their backs and they love to eat wood. This means an infestation of this invasive species can cause the death of dozens of trees, but can even cause some damage to wooden structures in buildings.
Black vine weevil
A black colored weevil that is notorious for its voracious appetite and willingness to eat just about any kind of fruit. These weevils do not fly. These weevils are hard to find, but they cause great damage to plants growing in containers.
Strawberry root weevil
A brown beetle that loves to prey upon the roots and above-ground portions of the strawberry plant. These weevils are found all across North America, in the United States and across Canada. The adults are only about six millimeters long and will often be found within the leaves of strawberry plants.
Pale green weevil
Hard to see because they are green and blend in with the plants they love to devour. These weevils are a broad-snout type of weevil and can fly. They are also sometimes known as leaf weevils.
How to get rid of weevils
The problem with weevils is that by the time most people realize they have them, it’s too late and too difficult to get rid of them within the stores of flour, rice or other food. Weevils lay a lot of eggs within the plants they devour and once they hatch and infest the food, they are too pervasive to be rescued. This is why weevils can be so expensive for businesses in the food industry because often the entire food shipment and stores of grain have to be disposed of.
The best way to get rid of weevils is to make sure they never get a foothold within the food stores. This means storing any stores of flower or rice in cold areas that are secured. Make sure the food is inspected before it’s stored next to other bags or stores of food. Weevils can jump from one box or bag to another.
Weevils do not survive well in cold environments, so reducing the temperature can stop weevils. Making sure the storage areas around your warehouse are scrubbed clean to ensure larvae is removed and weevils do not develop.
For restaurants and other businesses with food, store flour and grain in small amounts. This can reduce the risk of weevils, too.
Remember, weevils can be transported across borders and from other parts of the world. Shipments of food, flour, wheat, rice, and timber can be treated to get rid of weevils before they end up in areas where the insects can establish a foothold.
Ehrlich Pest Control gets rid of weevils
Ehrlich has treatment programs for food service and food storage businesses. We have been servicing businesses in those industries for decades now and understand the very sensitive nature of getting rid of and preventing pests like weevils from infesting food stores.
Contact your local Ehrlich Pest Control office and discuss what your food business is and if you have concerns about weevils. We’ll work with you to get rid of these pests and prevent their return.
How To: Get Rid of Weevils
No matter how scrupulously you clean your kitchen, you may still open your cabinets one day to find them crawling with tiny beetles. Unlike insects that enter through doors, windows, and crevices, weevils sneak in with your groceries. The adults chew into grains and lay eggs, making it virtually impossible to tell if you’ve purchased a sack of something that contains larvae.
Of the some 60,000 species of weevils, the ones that threaten your larder are the rice and maize varieties (dark reddish-brown with red or yellow spots, about 1/16-inch long) and the larger, shiny, dark brown-to-black grain weevils. But have no fear! The following step-by-step will walk you through how to get rid of weevils for good.
By the time you spot weevils, odds are they’ve infested other nearby food items. So in order to oust them, you’ve got to purge your pantry of unsealed dry foods, including oats, rice, barley, flour, corn meal, pasta—even pre-packaged box-type dinners that don’t have sealed internal pouches. And don’t stop there: If boxed products have sealed airtight bags inside, toss the box and label the bag with an indelible marker. Do this even for boxed products weevils won’t eat, such as gelatin, because the pests might have entered the box and could later emerge to re-infest new products.
Put salvageable foodstuffs in the freezer for four days, which will kill any larvae that might be hiding in the product. Items you don’t think will withstand freezing—dried herbs, for instance, that may lose their zing—can go in a sealed bag or container and be stored elsewhere. Before returning anything to the shelves, proceed to Step 3.
Thoroughly clean the pantry and cabinet shelves. Everything has to come out—canned goods, spices, aluminum foil, whatever you store in there—in order to get rid of every weevil. Vacuum the shelves, making sure to get the nooks and crannies, and then take your vacuum outside to dump its canister. Wipe down the entire vacuum (canister included) with disinfectant before bringing it back inside. Sponge all shelving and cabinet interiors with either hot soapy water or spray cleaner, and let dry thoroughly.
Finally, spray shelves and cabinet interiors with a household insecticide labeled as effective for killing weevils. Note that the formulation need not be chemical based. Many homeowners have reported success with non-toxic options like ERADICATOR, which you can find at home centers and through online retailers like Amazon. No matter your chosen insecticide, be certain to follow all the manufacturer’s safety precautions. Circumstances depending, that may or may not involve keeping children and pets away from the pantry temporarily. Likewise, note that it may be necessary to clean the area one last time before re-stocking the shelves.
Sure, these four easy steps can get rid of weevils in an afternoon. But since any and all innocent-looking dry food packages could contain weevils, the only sure way to prevent another infestation is to put dry staples, such as rice, beans, lentils, quinoa, wheatberries, macaroni, and cereals in the freezer for four days after purchase before stowing them. Alternately, store these items in individual sealed plastic or glass containers. While these suggestions might seem like overkill, all it takes is one female weevil to start another invasion.