- How to Get Rid of Eastern Tent Caterpillars
- Eastern Tent Caterpillars
- Western Tent Caterpillars
- Forest Tent Caterpillars
- Other Insects That Are Mistaken for Tent Caterpillars
- Tent Caterpillar Lifecycle and Control
- Life Cycle
- Tent Worms: Tent Caterpillar Home Remedy
- About Tent Worms
- Tent Caterpillar Removal & Tent Caterpillar Home Remedy
- How to Kill Tent Worms
- What Are Worm Nests in Trees?
- Fall Webworm
- Eastern Tent Caterpillar
- Fall Webworm – Trees
- TENT CATERPILLAR FACTS & CONTROL
- So… What’s a Tent Caterpillar?
- What’s NOT a Tent Caterpillar?
- Reproduction Patterns of Tent Caterpillars
- Tent Caterpillar Habitat
- Symptoms of Tent Caterpillar Damage
- Results of a Tent Caterpillar Infestation
- Natural & Organic Controls
- How to Stop Caterpillars and Cankerworms with Tree Banding
- Tree Bands – Treatment for Worms, Cankerworms, Gypsy Moth or Caterpillars
- Solutions for Gypsy Moth
- Trednot Slippery Caterpillar Barrier Tape 30 ft Roll
- Bonide 252 16 oz Captain Jacks Dead Bug Brew Concentrate
- Stop Fall Webworms the Organic Way
- Strategy 1: They’re Only Ugly
- Strategy 2: Remove the Webs
- Strategy 3: Encourage Beneficial Insects
- Strategy 4: Use Bt
- Strategy 5: Spray with Neem
How to Get Rid of Eastern Tent Caterpillars
If you notice web-like structures between branches of your trees, including your ornamental and fruit trees, then you may be dealing with a common pest found all over North America: the tent caterpillar. These pests are actually the larvae of several types of moths that make their home in your trees and feed on plant leaves. Tent caterpillars are aptly named for the conspicuous, silk tents they build in the branches of host trees.
With severe infestations, they can defoliate your trees. By learning how to get rid of tent caterpillars and finding safe control methods, you’ll help save your plants from threatening infestations.
Your location can determine which type of tent caterpillar you’re dealing with and the best control methods.
Eastern Tent Caterpillars
Eastern tent caterpillars are common in the Eastern U.S and the Rockies. Their populations vary by year, and large infestations can cause extensive damage to the appearance of ornamental trees. As soon as eggs hatch, the caterpillars climb up into the bends of trees to spin webs.
You may find them in a variety of common host trees.
Eastern tent caterpillars have black hairy bodies with yellow stripes and oval-shaped blue dots along their sides. They are often confused with gypsy moths, which look similar to eastern tent caterpillars, but they lack one distinguishing mark: a white stripe that runs down their backs. Gypsy moths do not have this stripe.
Western Tent Caterpillars
Western tent caterpillars and forest tent caterpillars are common in the Northwest, but western tent caterpillars are also found on certain host trees in the southern Rocky Mountains. The two are about the same size, but differ in other areas.
Western tent caterpillars are orange with black markings that run down their backs. Their “tents” begin emerging in spring as their eggs hatch. At this time, trees begin to bud and these pests begin feeding on new growth immediately after hatching. You can find them on a variety of host trees, including:
- Wild Plum
- Fruit trees
Forest Tent Caterpillars
Forest tent caterpillars have a noticeable appearance. You can easily identify them by their blue color with black specs, and the white, foot-printed-shaped markings on the center of their backs. Their webs are also silken mats between tree branches, and they aren’t considered actual “tents.” Some host trees include:
- Sugar Maple
Other Insects That Are Mistaken for Tent Caterpillars
There are other types of moths and insects that are commonly mistaken for tent caterpillars. They have varying effects on your property.
Gypsy moths differ from tent caterpillars, which means gypsy moth caterpillar control methods will differ slightly as well. Gypsy moths don’t appear in the spring, but instead appear later in the year. One generation appears each year, and they affect a range of ornamental shrubs, conifers and trees. You may also notice them on fruit bushes.
If you hear someone referring to tent worms, they may be talking about fall webworms. These are not tent caterpillars, but at times, people use the two names interchangeably. They differ from eastern tent caterpillars in appearance and habits — fall webworms are creamy-white, hairy, and have dark spots.
They spin webs over the tips of branches and leaves, and they also feed within their webs unlike tent caterpillars who use their tents as shelter. As the name implies, fall webworms are most active during fall.
Tent Caterpillar Lifecycle and Control
Understanding the pest’s lifecycle is important when you’re killing tent caterpillars or getting rid of a caterpillar infestation. Eastern tent caterpillars make their first appearance in early spring and complete their lifecycle by summer. This means host trees have time to grow new foliage and generally don’t die due to an infestation. However, they can damage a tree’s appearance and health.
Eastern tent caterpillars lay eggs in host trees from January through March. Eggs begin hatching in early spring, and the larvae feed and develop into adults over the next few months. Adult moths begin laying new batches of eggs in the summer and continue through fall and early winter.
Since eggs are dormant during winter, you can spray trees with an oil to smother the eggs. Safer®Brand BioNEEM® is a neem oil concentrate that kills the eggs of a variety of insect pests, including caterpillars. This product works by disrupting the insect’s hormonal balance, so they are killed before they molt into their life stage. BioNEEM® contains azadirachtin, which is a natural Insect Growth Regulator extracted from the neem seed.
If you don’t start controlling the caterpillars while they are dormant, you can also use a spray such as Safer®Brand Caterpillar Killer that kills pests at all stages of development. This product is a method of getting rid of caterpillar infestations. Caterpillar Killer contains Bacillus thuringiensis var. kurstaki, a natural ingredient that doesn’t harm people, birds or other animals. However, it does kill caterpillars within a few days.
This product is ideal for:
- Forest tent caterpillar control
- Western tent caterpillar control
- Eastern tent caterpillar control
- Fall webworm control
- Gypsy moth control
- Green step caterpillar control
Other methods of getting rid of tent caterpillars include pruning and introducing natural predators. Caterpillars have natural enemies, such as birds and wasps. Predators pick these pests out of trees and eat them. If the caterpillars’ tents are within reach, you can also consider pruning off the infested branches and burning them to get rid of tent caterpillars.
By: Wizzie Brown
Tent caterpillars attack several species of broadleaf trees and shrubs, producing unsightly webs, or tents. When their populations become large, the caterpillars can defoliate trees, stunting their growth. They attack ornamental and fruit trees.
The keys to eliminating tent caterpillars are identifying them early and accurately, understanding their life cycle, and using appropriate cultural or chemical control measures.
In Texas, four closely related, troublesome species are the eastern tent caterpillar, Malacosoma americanum; the western tent caterpillar, Malacosoma californicum; the Sonoran tent caterpillar, Malacosoma tigris; and the forest tent caterpillar, Malacosoma disstria.
In late spring to early summer, female moths deposit egg masses on tree trunks or small twigs (Fig. 1). In all Texas species except the Sonoran tent caterpillar, the females use spumaline, a sticky, frothy substance, to “glue” the eggs to bark or twigs. The spumaline also serves as a hard, protective covering around the egg mass.
Egg masses remain on the trees during most of the summer, fall, and winter. Caterpillars, or larvae, hatch from the eggs in early spring about the time the leaves on their host plants emerge. Within a few days, eastern and western tent caterpillars feed on these new leaves.
Tent caterpillars form small webs and enlarge them as they grow. The web is most often found in a crotch of small limbs (Fig. 2) and protects the larvae at night and during rainy spells. Because the larvae move from their tents to feed on leaves, damage can occur some distance from the web. Defoliation is often concentrated because tent caterpillars feed in groups.
Eastern and western tent caterpillars form large, conspicuous webs. The Sonoran tent caterpillar spins a small web when it molts but does not live in it at other times.
As they grow, the larvae molt or shed their skin several times. During growth stages, or instars, caterpillar size progresses between molts from small (⅛ inch) to large (1¾ inches). The color pattern can also change from instar to instar.
One of the most common tent caterpillars is the forest tent caterpillar (Fig. 3). It does not build a tent but spins a loosely woven resting mat on trunks and larger branches. Dozens of caterpillars may congregate on these mats between feedings.
As forest tent caterpillars complete their development in late spring, the larvae move several yards and may feed on a variety of herbs, shrubs, and trees before finding a site on which to spin a cocoon for pupation. Common sites include protected places such as in the web, under bark, in dead plant material on the ground, inside a rolled leaf, or under the eaves of houses. Forest tent caterpillars often draw leaves together to form a cocoon site.
Cocoons are loosely constructed of silk and have a white or yellowish crystalline substance scattered throughout the mass. Do not handle cocoons because the crystalline substance can irritate skin.
Adult tent caterpillars are brown and yellowish moths with two diagonal markings on the front wings (Fig. 4). Their wingspans are about 1 inch. These moths are attracted to lights.
All tent caterpillar species have one generation per year. Adults live for only a few days, during which they mate and lay eggs and do not feed.
Immature tent caterpillars are colorful and about 1¾ inches long when fully grown. They have a few long hairs on their bodies, mostly along the sides. Individual species are identified by larval coloration and markings.
If you find tents with larvae that do not match the descriptions in Table 1, they are probably fall webworms. Fall webworms can have several generations per year and produce tents during late summer and fall. (For more information, see Texas AgriLife Extension Service publication E-233, Fall Webworms available at http://AgriLifeBookstore. org.)
Base your management program on the amount of defoliation, unsightly webs, and the nuisance the caterpillars cause. For best control, you may need to use a combination of cultural and chemical techniques.
Cultural control. During winter pruning, inspect the trees for egg masses, which appear as swellings on small, bare twigs. Normal pruning often removes the tent caterpillar eggs before they hatch. Dispose of the egg masses pruned from the trees.
Prune twigs containing webs when you first notice them in the spring. If they are in areas where you cannot or do not want to prune, destroy the webs by hand using a long pole or high-pressure water spray. Burning the web and caterpillars is hazardous and not recommended.
Kill caterpillars knocked from the tree or crawling around the home by crushing them or placing them in a bucket of warm, soapy water. Sweep up the dead caterpillars and dispose of them.
Biological control. Beneficial insects can reduce tent caterpillar populations. Parasitic wasps in the genera Cotesia, Bracon, and Hyposter attack the larval stage of tent caterpillars. Trichogramma species attack tent caterpillars eggs. Birds, lizards, and insects such as assassin bugs and paper wasps also feed on tent caterpillars.
Chemical control. Before spraying for tent caterpillars, consider that although the individual leaves already fed upon will remain damaged, trees that have been defoliated early in the season will usually put on new leaves. It is useless to spray if the tent caterpillars have been allowed to feed and complete their development. Even so, removing the tent will eliminate the unsightliness of the tent itself. Tents are resistant to weather and will remain in the tree a long time unless they are removed.
Insecticides can be used on webs as a spot treatment. Apply them in the early morning or evening to concentrate the spray on the tents when the caterpillars congregate.
During the winter, smother the eggs by spraying them with dormant oil, a highly refined oil that spreads uniformly and coats dormant insects and eggs. The product label will include which species may be sprayed with these oils. When using horticultural (petroleum-based) oils, spray the plant well, since the level of control depends on the thoroughness of the coverage.
Some naturally derived products include active ingredients such as Bacillus thuringiensis (Bt) variety kurstaki, spinosad, or insecticidal soap. These products work best on smaller caterpillar stages. When spraying Bt kurstaki and spinosad on foliage, spray the plant thoroughly so the product will be picked up and eaten by the caterpillars. Bt is selective in that it targets only caterpillars, while spinosad works on insects that chew a lot of foliage. Insecticidal soap is a contact-kill insecticide and must be sprayed directly on the caterpillars to kill them.
Plant-derived insecticides include active ingredients such as pyrethrum and d-limonene. Some of these formulations work when they come into contact with the pest, while some may have an oil-based component similar to horticultural (petroleum-based) oils. Both petroleum-based and plant oils must be applied with good coverage directly to the pest to ensure that the product works properly.
Many longer-lasting, synthetic pesticide products provide faster, longer-lasting control than do most plant-derived insecticides and work on all growth stages of the caterpillar. However, most of these products can kill beneficial insects as well as the caterpillars. Active ingredients to look for include bifenthrin, cyfluthrin, esfenvalerate, fluvalinate, permethrin, lambda-cyhalothrin, indoxacarb, acephate, and carbaryl.
Professional pest management providers have access to products with the active ingredient chlorantraniliprole which are not available to homeowners without a pest management license.
Pesticide users are responsible for the effects pesticides have on their own plants or household goods as well as any problems caused by drift from their properties to neighbors’ properties or plants. Also, regulations on insecticides and pesticides are subject to change. For the most reliable instructions, always read and carefully follow the instructions on the product label.
The author wishes to thank Bart Drees, Glen Moore, and Kim Schofield for review of this manuscript. All images courtesy of Bart Drees.
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I noticed a few webby tents in a mulberry tree this week and, as I recommend to others, I studied them to identify the pests.
The tents are at branching points in the trees, not at the end of branches. The caterpillars were using the tent for daytime protection rather than enclosing their food source. The caterpillar has a white stripe down the center of its back and oval blue spots on either side of the stripe.
These clues and the timing, late spring to early summer, lead me to the conclusion that my problem was Eastern tent caterpillars (Malacosoma americanum), a native pest.
Adults are reddish-brown moths with two pale strips diagonally across the back of the folded wings. The damage they do generally is only aesthetic and the trees usually completely recover.
The location of the webs and the time of year eliminated bagworms.
These tend to appear later in the season and their webs are built on the ends of branches, enclosing the leaves that they are feeding on.
The physical appearance of the caterpillars eliminated gypsy moth.
Although both pests are about 2 inches long, the gypsy moth does not have a white strip and the spots on its back are, according to the U.S. Department of Agriculture description, pairs of blue and red.
Also, gypsy moths do not build web tents.
The treatment depends on the extent of the infestation. I only had a few tents in one tree. They were easily cut out and destroyed. The tents can be dunked in soapy water or burned, a good job for one of my favorite tools, the flame weeder. Of course, the tents must be removed before burning — no flaming tents in the trees!
Another alternative, one that I would have used had I found it first, is to use a stick and break open the tents. This provides a feast for the local bird population. It would also be a reasonable solution for a much larger infestation or in situations where it is not feasible to remove and destroy the tents.
Bt (Bacillus thuringiensis) is a biological control that can be applied to the leaves of the infested plant while the caterpillars are small. Be sure to use one specifically directed at caterpillars but note that it does not differentiate; it will affect all caterpillars that come in contact with it.
One method of prevention is to look for the bands of shiny brown eggs that can be seen in winter on infested twigs. Removing the egg masses eliminates the caterpillars before they become a problem.
For additional information and photos, check the USDA website:
Often in an effort to attract wildlife, we create our own problems.
We set out birdbaths and feeders to attract birds then complain when they raid our bean plants, eat our strawberries and dig up our sunflower seeds before they have a chance to sprout. We plant nectar plants for butterflies then spread Bt to kill caterpillars that munch our dill, parsley and fennel.
What’s the solution? Learn to share the garden. Plant extra seeds or put in more mature plants. Use barriers such as netting or fencing to protect those plants most important to you. Be creative. In our garden, I just write off the elderberries — the birds always get them.
The tomatoes grow in large pots, cherry tomatoes hang in baskets from shepherd’s hooks. Both solutions make it more difficult for the groundhogs to get to the plants. My lettuce and cabbage, container varieties, are doing well in window boxes on the back deck. Two large pots hold zucchini plants, again bred for containers.
Feeding the birds all season seems to cut back on the damage to seedlings. Letting the snakes stay under the wood storage rack cuts back on the voles and other small rodents. Providing shady nooks and upturned pots gives the toads a safe haven and in return, they keep the slug damage to a minimum. Allowing an unmown patch gives the butterflies a variety of flowers and host plants to choose from. In return, we get a larger, more diverse butterfly population.
Local ecology program
Ecological restoration: Wildlands Conservancy and Penn State Cooperative Extension are offering a free program on June 23. The presentation will highlight the variety of ecological restoration projects currently under way or completed in the Lehigh Valley. Several stream restoration projects and the land reclamation project at Lehigh Gap will be included in this tour. Call Maureen Ruhe at 610-965-4397, ext. 136 for additional information.
Sue Kittek is a freelance garden columnist, writer, and lecturer. Send questions to Garden Keeper at [email protected] or mail: Garden Keeper, The Morning Call, P.O. Box 1260, Allentown, PA 18105.
This Week in the Garden
•Plant additional crops of snap or pole beans, radishes, and carrots at two-week intervals. Harvest regularly, at least every other day.
•Check planters often; water frequently.
•Divide spring blooming perennials after they finish blooming. Japanese primrose can be divided now. Cut back boltonia by half the size of the plant. Cut Joe-pye weed back to 3 feet tall. Cut back candytuft to encourage bushiness. Shear back woodland phlox (P. divaricata)
•Deadhead sea thrift (Armeria), centaurea, centranthus ruber, dianthus, fringed bleeding heart (Dicentra exima), hardy geraniums, bearded irises, red hot poker (Kniphofia uvaria/tritoma), catmint (Nepeta), herbaceous peonies, oriental poppies, pincushion flowers (Scabiosa)
•Fertilize Siberian irises, summer phlox (P. paniculata) and Shasta daisies with a light application of balanced fertilizer
•Start pinching back helenium, chrysanthemums and asters to promote bushy growth and more flowers. Continue to pinch back new tips at two-week intervals until early July.
•Stake tall flowers; train vining flowers and vegetables.
•Weed regularly and cut off flowers of any weeds you don’t get to.
•Rake and fluff old mulch; apply new mulch as needed but keep depth to a maximum of two to three inches.
•Buy annuals and tender perennials or tropicals for pots, window boxes and to fill in bare spots until perennials and shrubs grow to mature size.
•Finish spring lawn fertilizer treatments this week.
•Cut lawns only when needed; use fresh gas and a sharp blade.
•Send winter snow removal equipment for seasonal tune-up or repair.
Tent Worms: Tent Caterpillar Home Remedy
Eastern tent caterpillars (Malacosoma americanum), or tent worms, are more of an eyesore or slight nuisance rather than an actual threat. However, getting rid of tent caterpillars is occasionally necessary. We can look at how to prevent tent worms and how to kill tent worms, if necessary.
About Tent Worms
Although often confused with fall webworms, tent caterpillars are quite different. Tent worms are active in early spring while webworms become active near fall. Tent worms make their tent-like nests in the forks of branches while webworm nests are located at the ends of branches. Fall webworms also enclose foliage or leaves within these nests. Tent caterpillars do not.
Tent worms prefer wild cherry trees and other ornamental fruit trees. They will, however, nest in ash, willow and maple trees as well. Other
than their webs making trees appear unsightly, tent caterpillars rarely cause major problems. However, large colonies can significantly defoliate trees, as they feed on the leaves. This usually does not kill trees, which generally develop new leaves, but may make them more susceptible to disease and other problems. Tent caterpillars may also snack on nearby plants.
Tent Caterpillar Removal & Tent Caterpillar Home Remedy
When tent caterpillar removal is necessary, the nests or egg cases can usually be picked out by hand. Egg cases can be seen easily once leaves drop from trees in fall. Larger nests can be removed by winding them around a stick or pruned out and destroyed.
The best time for tent caterpillar removal is early morning or evening while they’re still likely to be in the nest. Introducing natural enemies, such as various types of parasitic wasps, can also help reduce tent worm numbers. Creating a welcoming environment for birds is also an excellent tent caterpillar home remedy.
How to Kill Tent Worms
Sometimes getting rid of tent caterpillars means killing them. While small infestations can be taken care of by dropping the nests into soapy water, contact insecticides work best for larger populations. Bacillus thuringiensis (Bt) is the most effective. Since this is a selective insecticide, it kills tent caterpillars while remaining safe to other wildlife. Apply spray directly to foliage and tent worm nests.
Getting rid of tent caterpillars is easy if you follow these basics steps. Your trees will return to their former beauty in no time at all.
What Are Worm Nests in Trees?
A tree covered in unsightly web nests can be frustrating. The webs themselves are unattractive, but they also catch dirt and debris for as long as they remain in the tree. If you have these web nests in your tree you could have an infestation of caterpillars. Both the eastern tent caterpillar and the fall webworm spin nests in trees. Fortunately, controlling these pests is simple.
Fully grown webworms are pale green caterpillars with long white hairs growing from black and yellow warts all along their bodies. Adult moths vary from all white to white with black spots. As soon as larvae hatch they spin a web of silk over the foliage where they feed. As they grow, they enlarge the web to enclose more foliage. Once mature, they drop to the soil to pupate. These caterpillars can defoliate trees but they don’t often kill them.
Eastern Tent Caterpillar
The eastern tent caterpillar is black with a white stripe along its back and rows of blue dots along its sides. The entire body is sparsely covered with hairs. As soon as caterpillars hatch, they spin silvery, conical tents of silk at branch crotches. The tents offer protection from the elements and from predators and as the caterpillars grow, their tents enlarge. Eastern tent caterpillars feed in colonies and can defoliate trees by early summer. As they move around the tree, they leave a trail of silk behind them. During large infestations, entire trees can be covered in silk from tents and from wandering caterpillars.
Bagworms also spin a protective shelter out of silk but theirs are somewhat different from the eastern tent caterpillar and webworms. Bagworms include bits of organic matter along with silk in the protective covering they spin on trees. Bagworms tend to feed on conifers and occasionally the bags they make are mistaken for pine cones. Older larvae are capable of defoliating conifers and deciduous trees. Successive infestations over many years can kill the host tree.
Web spinning caterpillars are easily controlled by mechanical methods. Find and remove egg masses in the spring to prevent infestations. Destroying webs with a long pole or hook can expose caterpillars to predators. Picking the bags of bagworms off trees can control them as well. Sprays containing the bacterium Bacillus thuringiensis var. kurstaki are effective and safe for people, animals and beneficial insects. If you feel insecticides are warranted, spray them in the spring when caterpillars are still small.
Fall Webworm – Trees
Fall webworm (Hyphantria cunea) caterpillars may feed on more than 100 species of deciduous forest and shade trees. Preferred hosts include mulberry, walnut, hickory, elm, sweetgum, poplar, willow, oak, linden, ash, apple, and other fruit trees. The adult moths are about 3/4 inch long. The wings are all white or white with black spots. Mature larvae are about 1 inch long and may occur in two color forms: those with black heads are yellowish-white, and those with red heads are brown. Both color forms have paired black tubercles running down the back. They are covered with long, silky gray hairs.
The caterpillars produce a web of fine silk over terminal branches. They only feed inside the web, which they enlarge as they grow. Look on the south side of tree crowns for the first sign of webbing. The webs may become messy, but the caterpillars rarely consume enough terminal growth to affect the tree. The first generation begins in May and is usually small. The second-generation caterpillars are present from August through October. The dry webs hang on terminals into the winter.
Prune out webbed terminals as they are detected. Pole pruners are useful for removing tents in trees. Bt (Bacillus thuringiensis, var. Kurstaki), horticultural oil, or insecticidal soap is recommended to control young larvae in large infestations and protect beneficials. There are 75 species of predators and parasites that normally keep this pest below damaging levels. Whatever you do, don’t try to burn them out!!
TENT CATERPILLAR FACTS & CONTROL
The worst thing about tent caterpillars are the tents themselves. These ugly blemishes can ruin a great view of a forest and make the trees in your yard look like they’re infested. Even worse, these tents hold the leaf-killing caterpillars that devastate your trees and shrubs.
Are tent caterpillars taking over your trees? Are they wiping out leaves? You can take steps to eliminate these creatures and prevent further damage to your trees. For instance, Safer® Brand Garden Dust is an OMRI Listed® treatment that kills over 20 varieties of caterpillars and worms – just what you need to rescue your trees!
So… What’s a Tent Caterpillar?
Adult tent caterpillar aren’t caterpillars at all, they’re moths. These moths are usually tan or brownish in color with a wingspan reaching up to 1 ½ inches.
The larvae – the caterpillars – are black with rows of white dots or stripes the length of its body. Short hairs cover their body, which can be up to 2 1/2 inches long.
The eggs are laid as a group in a tube-like wrapping that encircles a tree branch or twig. These masses can contain up to 350 eggs and hatch in the spring. If you spot one of these egg masses, which makes a section of the branch look shiny and engorged, cut the branch below that point and dispose of the egg mass in the trash.
What’s NOT a Tent Caterpillar?
There are many similar caterpillar/moth species that look a lot like tent caterpillars:
- Army Worms – These destructive pests target crops and lawns rather than trees. They grow up to 2 inches long and are hairless.
- Bagworms – These worms don’t look like a tent caterpillar, instead they are pudgy and hairless. Their nests, however, may make you assume they’re tent caterpillars. Bagworm nests are made of webbing, but appear messy and filled with pieces of plant debris.
- Gypsy Moths – These caterpillars have a yellow heads and a hairy body. Five pairs of blue dots, followed by six pairs of red dots, run along the length of their body. It’s easy to confuse Gypsy Moth Caterpillars and Tent Caterpillars. Luckily, both can be treated with the same Safer® Brand products.
Also be aware that there are multiple species of tent caterpillar. In the U.S. and Canada, others include western, forest and southwestern tent caterpillars. Forest tent caterpillars, by the way, don’t actually use tents – instead they congregate in social clumps on the trunk of a favorite tree.
Reproduction Patterns of Tent Caterpillars
Female moths deposit their eggs in the middle of summer. The eggs overwinter in a protective case that’s attached to an the branch or twig. The eggs hatch in the beginning of spring.
Emerging caterpillars spin a protective silk tent in the crotch of a tree. They feed on nearby leaves in the daytime, returning to their nest when finished. They will continue in this manner for the next month or two until they are ready to pupate.
During the next phase of its life cycle, the tent caterpillar will leave the nest and find an appropriate trunk or plant debris on which to spin its own cocoon. After 10 days to two weeks, the adults emerge as moths and the cycle continues. The tent caterpillar has one generation per year.
You can prevent tent caterpillar damage by eliminating the insects with a product such as Safer® Brand Garden Dust.
Tent Caterpillar Habitat
Found throughout the United States and Canada, these caterpillars prefer trees and shrubs of the hardwood deciduous variety, and cherry trees appear to be their favorites. Look for tent caterpillars in these trees and bushes:
- Oak Ash
- Sugar maple
- Wild Cherry
Widely recognized by their webbed (silk) tent structures, these larval insects can cause mass defoliation in a short period of time. Damage is relegated to the tree or bush where their tent is located. The species spreads to new trees when mature moths venture out to lay eggs.
Symptoms of Tent Caterpillar Damage
Leaves within three feet of a tent worm nest will disappear first. In other instances, an entire leaf cluster may be consumed. Additionally some trees may lose so many leaves that it appears to have dropped them in preparation for the autumn.
The most important symptom, though, is that you’ll see the tent caterpillars’ web structures. These nests are easy to spot, even when foliage is at its height in the early summer. As the caterpillars consume more and more nearby leaves, the tents will be even more evident.
Why do tent caterpillars create their silk tents? Caterpillars use them for shelter, and they enter them at night and during rainstorms. They tents may trap heat, too, allowing them to survive in the early spring and during chilly nights. The thick mass of silk also protects them from birds and other predators.
The web nests may also survive through the winter. Those that do will look ragged and dull compared to new creations.
When it’s time to spin cocoons, dozens of tent caterpillars will descend from their food source to the ground below. From there, you may spot them crossing roads and sidewalks as they search for the perfect spot to prepare for their transformation into moths.
Results of a Tent Caterpillar Infestation
Trees are often defoliated by tent caterpillars, especially if the infestation is a large one. These attacks are rarely fatal to the plant, though. It’s only after repeated attacks across multiple years that a weakened tree perishes, usually because it doesn’t have the strength to fight off another pest or an opportunistic disease.
Tent caterpillar infestations may also trigger a second, stunted rebud of leaves in the same season. The stress of the caterpillar attack and following rebud often stunts the tree’s growth for the next few years. However, if caterpillars are successfully treated, the tree should grow normally again.
Natural & Organic Controls
Safer® Brand offers a variety of options to control an infestation of tent caterpillars. These options are all OMRI Listed®, meaning they are compliant for use in organic gardening.
Safer® Brand Garden Dust and Safer® Brand Caterpillar Killer II With B.T. Concentrate are OMRI Listed® products that can be used to help control tent caterpillars. Each uses B.t. (Bacillus thuringiensis), a biological control that the caterpillars accidentally consume while attempting to feed normally.
Safer® Brand End ALL® is another option for fighting tent caterpillars.
When ingested, B.t. kills tent caterpillars, preventing further damage to your trees. The caterpillar eats the B.t. which is spread in powder form on leaves. Once ingested, it works as a gut rot poison that makes the caterpillar stop feeding. Once the caterpillar stops feeding, it dies within days, succumbing to malnutrition.
B.t. can be used on more than 20 caterpillar and worm species, but it has no effect on birds, earthworms or beneficial insects.
For even more options, explore the tent caterpillar control product page for details on Safer® Brand End ALL®. You can learn how each of these solutions target caterpillars and how they should be applied. Remember to carefully read and follow all directions on the product’s label.
Safer® Brand’s B.t. products are very specific in how they target caterpillars and leaf feeding worms. B.t. will not harm children, pets or wildlife. It is recommended with any pesticide to test plants for sensitivity to the product. Spray a small section of the plant in an inconspicuous area and wait 24 hours before applying across the entire plant.
B.t. products should be applied when it is cooler, preferably later in the afternoon or early in the evening since the product breaks down in sunlight and heat. Carefully read and follow all directions on the product’s label.
When applying a product with pyrethrins, which is used in Safer® Brand End ALL®, to infested plants, carefully read and follow all directions on the product labeling for application instructions. Do not spray End ALL® on plants in the peak of the day or when temperatures exceed 90°F.
Safer® Brand leads the alternative lawn and garden products industry, offering many solutions that are compliant with organic gardening standards. Safer® Brand recognizes this growing demand by consumers and offers a wide variety of products for lawns, gardens, landscapes, flowers, houseplants, insects and more!
The larvae of several moth and butterfly species (listed below) are collectively referred to as tent caterpillars. Distributed throughout much of the United States and Canada, these caterpillars multiply rapidly and can defoliate a large number of deciduous trees and shrubs in a short time. They are often seen on roadside trees and in neglected orchards. Besides defoliation the larvae produce large unsightly webs, or tents, in the crotches of tree branches. These webs are used to protect the caterpillars from predators and the elements. Although tent damage is unsightly, infestations rarely threaten the lives of trees. Four species are commonly discussed:
Eastern Tent Caterpillar (Malacosoma americanum) – Found east of the Rockies and north into southern Canada. Full grown caterpillars (2 inches long) are sparsely hairy and black in color with a row of pale blue spots on each side. They have a white stripe down the center of their backs that makes them easy to identify. Adults (1-1/2 inches long) are reddish brown moths with two white bands running diagonally across each forewing. Host plants include cherry, apple and crabapple, but may be found on a variety of shade trees as well.
Western Tent Caterpillar (Malacosoma californicum) – Troublesome in the northern and western portions of the United States and adjoining Canada. These hairy caterpillars (2 inches long) are yellowish-brown in color and have a row of blue spots on their backs, with orange spots interspersed in between. Adult moths (1-1/2 inches long) are orange-brown in color with two narrow yellow lines on the wings. Willow, poplar, cottonwood, birch, apple, plum, cherry, roses and oak are favorite host plants of this pest.
Forest Tent Caterpillar (Malacosoma disstria) – Found throughout the United States and Canada wherever hardwoods are found. Despite its name, this pest does not spin a true tent; instead, it forms a silken mat on the surface of branches where they congregate. Larvae are similar in appearance to M. americanum but have a series of keyhole-shaped white spots running down their back instead of a solid line. Adults are light yellow to tan colored moths (1-1/2 inch long) with two dark bands on their forewings. Host plants include wild cherry, aspen, maple, oak and hawthorn.
Fall Webworm (Hyphantria cunea) – Common across North America and Mexico, webworms are known to feed on over 85 species of trees. Unlike tent caterpillars that build a nest in the crotch of trees, webworm tents are located at the outer ends of branches and often include leaves. Caterpillars (1 inch in length) are covered with long hairs and vary in color from yellow to green, with a black stripe on the back and a yellow stripe on each side. Their heads are either red or black. Adult moths (1 inch long) are pure white in color and usually have dark spots on the wings.
Most species of tent caterpillars overwinter in the egg stage. Dark brown to gray egg masses containing 150 to 400 eggs are attached around the small twigs of trees and shrubs. Hatching takes place about the time that leaf buds begin to unfold, usually in early spring. Caterpillars are gregarious and soon construct silken tents which they uses as a refuge during the early morning and evening hours and during rainy spells. They leave their protective tent and feed only during the day, laying down a silk trail as they crawl to help them find their way back to the shelter. Approximately six weeks after hatching, and five instars later, the larva become fully grown (up to 2 inches long, sparsely hairy). Pupation occurs in silken cocoons which are found on tree trunks, fences, or leaf litter. About two weeks later adult moths emerge and soon deposit the overwintering eggs. There is one generation a year.
Note: Larvae can be a nuisance when they begin to migrate to protected areas to pupate. They are often found by the thousands traveling over roads, streets, driveways, walkways, fences and buildings.
How to Control
- Scrape off and discard overwintering egg masses and tear the protective tents out by hand before the larvae start to feed.
- Restrict caterpillar movement and cut off access to feeding areas with Sticky Tree Bands or Tree Tanglefoot Pest Barrier.
- The natural, soil dwelling bacterium Bacillus thuringiensis or Bt-kurstaki is particularly effective on inch worms of all types. Use easily applied spray to hit worms and protect the leaves at the first signs of damage. BTK sprays do not harm honey bees or birds and are safe for use around pets and children.
- Spinosad, another biological agent derived from fermentation, is also very effective. It’s the active ingredient in Monterey Garden Insect Spray, a product classified as organic by the U.S.D.A. National Organic Program and listed for organic use by the Organic Materials Review Institute.
- AzaMax contains azadirachtin, the key insecticidal ingredient found in neem oil. This effective spray disrupts growth and development of pest insects and has repellent and anti-feedant properties. Best of all, it’s non-toxic to honey bees and many other beneficial insects.
- Fast-acting 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.
Note: More than 80 species of predators and parasites have been identified in the United States, yet they are not commercially available. These insects play an important role in maintaining pest populations during most years. As a result, care most be taken when applying pesticides to minimize damage to these beneficial organisms.
If you’ve walked outside anytime in the last few weeks, you’ve probably seen tent caterpillars.
They’re the ones making web-like nests in trees and bushes. By now, the caterpillars are pretty big, and they gather on the tents, all waving around together in a somewhat creepy manner.
I’ve been curious about them, so I did some poking around to see what I could learn. I was also on the hunt for a photo of the adult moth, which I eventually found.
The tent caterpillar has a single life cycle each year. The caterpillars hatch and form nests in the spring. The tent-like nests are protection for the little caterpillars. The caterpillars will molt a few times, chomping away on leaves in between. Eventually they leave the nest behind and spin cocoons. After 12 to 18 days, the adult moths emerge. The moths mate and the females lay eggs. The moths die within a few days. The eggs hang out until spring, when the cycle begins again.
The tent caterpillars tend to go in cycles. They’ll be prevalent for a few years before dying back down. They have a number of natural predators including birds, wasps and beetles. While the tents are ugly, healthy trees rebound from the damage.
Most importantly, though, I wondered: What do these moths look like? Answer: They’re small and unremarkable. Brown with fuzzy antennas. Not shockingly, you’re way less likely to see them as they’re only around for a few days, rather than weeks or months.
More about tent caterpillars
Some impressive, close-up photos of the caterpillars
How to Stop Caterpillars and Cankerworms with Tree Banding
If tree pests, like cankerworms, ravaged your tree leaves this spring, chances are it could happen again.
Right now, cankerworms are about to settle in for the winter. They’re looking for a cozy home, a good place to lay eggs and another all-you-can-eat buffet come spring. Cankerworms love big, deciduous trees that lose their leaves in fall, like elm and oak. Though, they’ll frequently attack these tree species, too.
Stop these creepy crawlers before they wreak havoc with tree bands. Find out what tree banding is, how it works and when to set one up.
Tree Bands – Treatment for Worms, Cankerworms, Gypsy Moth or Caterpillars
What are tree bands? How do they stop critters, like cankerworms?
When you wrap a tree trunk in an insulating material covered with a sticky substance, you create a tree band. The band traps cankerworms, gypsy moths and other caterpillars that hike up your tree. Essentially, the pests get stuck on the band and can’t make it to your tree’s canopy to live or do any harm.
When should I apply a tree band?
For cankerworms, wait until most or all your tree’s leaves have fallen so that they won’t get stuck in the band. Generally, applying around Thanksgiving works well. If you’re stopping gypsy moths, add a tree band in late May.
To see if you caught fall cankerworms, check the band in early March. If it’s full, call your arborist again to see if it’s wise to implement tree bands again.
Do all my trees need tree bands?
If your trees are close together, add tree bands to all of them. Otherwise, the pests may be able to travel from one tree to the next. Then, since they’ll likely be traveling from branch to branch or canopy to canopy, the tree bands won’t deter them.
Solutions for Gypsy Moth
Trees attacked by gypsy moth, usually oaks, can be very large when mature. Don’t try to treat the gypsy moth yourself if you have a large tree. Larger trees should be treated by a professional arborist who will have the proper equipment and expertise. For example, a 30-foot tree will require about 10 to 20 gallons of spray material for effective control. This is best done by a trained applicator.
What Not To Do If Tree Is Defoliated
If the tree has been defoliated then there should be no crown thinning by arborists or fertilizing by anyone for at least two years after the last defoliation. Both these practices were common among tree professionals but have since been shown to be very harmful and stressful to the tree under attack.
For Smaller Trees There Are Some Non-chemical Techniques
Control With Burlap Barriers
Sometime in June or early July, gypsy moth caterpillars become night feeders and come down from the tree each morning, precisely at dawn. Then they go back up the trunk precisely at dusk, just like clockwork. You can take advantage of this behavior and trap them on their way back up the tree in morning.
For large trees, wrap a piece of natural burlap a foot wide around the tree trunk, about chest-high. For smaller trees the band should be no wider than half the diameter of the tree. Wrap the band around the tree, and tie the burlap strip at its center with heavy twine, letting the top fold over about half way to form a fold or skirt. Descending caterpillars will hide under the fold. In the late afternoon, put on garden gloves and sweep the caterpillars off the burlap into a container of detergent and water. For this technique to work effectively, you need to be prepared to deal with caterpillar disposal every day for several weeks. Burlap barriers can help reduce defoliation in light to moderate infestations.
Control With Sticky Barriers
Bands of sticky materials mounted around tree trunks also stop gypsy moth caterpillars as they make their way up and down tree trunks each day. You can buy commercial sticky bands to wrap around the trunk or your tree.
A do-it-yourself version involves wrapping a 4-inch-wide piece of cotton batting or similar material around the trunk of the tree, about chest high. Over this, tie a 6- to 12-inch-wide piece of tar paper smeared with an adhesive pest product such as Tanglefoot. Replace the band whenever needed until mid-July, at which time you should remove it. Sticky barriers can help reduce defoliation in light to moderate infestations.
Note: The U.S. Department of Agriculture cautions against applying any sticky substances, especially grease, tar, or other petroleum products, directly to the bark of trees; this can cause swelling and cankering.
Control With Slippery Barrier Tape
They steadily enlarge in size and by mid-July they are well fed and ready to pupate. By this time the caterpillars start to move up and down the trees; they climb down to hide during the day and climb back up at night to feed. When you put up the slippery tape they can’t get back up the tree. Real sneaky.
Trednot Slippery Caterpillar Barrier Tape 30 ft Roll
- Protects trees from caterpillars and other crawling insects
- Non-Chemical 2″ x 30 ft roll protects 25 four-inch trees
- Applied to the trunk of the tree as a slippery barrier
- The barrier is too slippery for caterpillars to climb across it.
- Stops defoliation from migrating caterpillars
Slippery Caterpillar Tape is a 30 ft roll of tape that is an adhesive on one side, to attach to the tree trunk, and slippery on the other side to prevent upward caterpillar migration. No Chemicals involved. Does not kill the caterpillars…they just go elsewhere. Used by homeowners to protect residential trees. Also used by fruit tree nurseries. To watch a video of the tape being used…past this in your address bar… www.you tube.com/watch?v=wq8oqPxLS8M (remove the space between you and tube
Destroy Egg Masses
In late April or May, search your yard for the characteristic fuzzy tan-colored egg masses. Scrape them off trees and other vertical surfaces with a putty knife or other flat instrument. Search the ground at the base of trees, too. Dump egg masses into a container of kerosene or paint the egg masses in place with creosote, or simply put on a pair of work gloves and smash them on the spot.
Organic Insecticide For Gypsy Moths
The decision to use insecticide to control gypsy moths depends on the condition of the trees or shrubs you want to protect. If they are healthy and vigorous they may not need spraying. If, however, they do need to be sprayed, you can treat small trees and shrubs with a backpack_sprayer. For small trees and shrubs up to 15 feet tall you will need a trombone sprayer.
So when you can see caterpillars, spray tree or shrub leaves thoroughly with a product containing Spinosad when the worms are actively feeding which will be early in the season. This will likely be sometime between May 1 to June 1, depending where you live. The gypsy moth caterpillars eat the Spinosad which is a bacteria that affects their digestion, when they chew on the leaves of the tree. They stop eating soon and die within a few days. Spray the entire area where the caterpillars are feeding as directed on the product label. We say again, in situations where the tree or shrub is very tall and difficult to reach, hire a professional arborist in the early spring to spray them properly and safely.
AzaMax will control gypsy moth caterpillars
AzaMax is a natural product with a broad spectrum of pest control and broad plant applications. AzaMax is an anti-feedant and insect growth regulator which control (kills) pests through starvation and growth disruption within two or three days. Therefore this product is used when the bugger is chomping on the foliage. Any of the sprayers can be used to apply AzaMax
For more information about AzaMax go to the Yardener’s Tool Shed;
Bonide 252 16 oz Captain Jacks Dead Bug Brew Concentrate
- Contains Spinosad, a naturally occurring soil dwelling bacterium.
- Kills gypsy moth caterpillars while they are feeding,
- 16 oz
- Easy to use in any kind of sprayer
Help Stressed Trees And Shrubs Recover
If you can reach the top of the tree or shrub with a backpack sprayer fitted with an extended wand, then you can spray the foliage and drench the roots with what is called a “bioactivator” or seaweed- or kelp-based plant tonic. This product contains seaweed extracts, hormones, enzymes, and other growth-enhancing substances. Feed the tree or shrub according to label instructions. Applying a tonic once a month until the end of the growing season is good therapy for a tree or shrub devastated by a massive gypsy moth attack.
Defoliated trees and shrubs may suffer further from lack of water. As soon as major defoliation occurs, keep the soil around the roots moist but not waterlogged. Water the soil 1 1/2 times the radius of the drip line very thoroughly every week, less if rainfall is sufficient. Also be sure to soak the soil thoroughly before the ground freezes in the winter. Put down a 4-inch-thick layer of mulch around the tree to buffer the ups and downs of temperature in the soil that can damage stressed roots.
Click here for more information on Using Mulch.
Stop Fall Webworms the Organic Way
It happens like clockwork. Your late-summer garden is looking great and then all of a sudden you see big, horrible webs in your trees and shrubs. Inside these webs are colonies of caterpillars munching away at your trees’ leaves.
Webworms are the caterpillar form of a small white moth. The moths fly around during the summer laying their eggs on the underside of tree leaves. The moths seem to prefer alder, willow, cottonwood, apple, pear, peach, pecan, walnut, elm, and maples, but will eat a very large variety of trees and shrubs.
As the eggs hatch, the caterpillars start to spin a web around the leaves they’re on. They feed for about six weeks and their webs can reach more than 3 feet across. This is when they look their worst.
Strategy 1: They’re Only Ugly
Before panicking, the first thing you should know is that these webworms don’t typically cause a lot of damage to trees and shrubs. They look far worse than they are. So if you don’t mind them, the most organic approach is to simply let them be. Even if they defoliate your tree, it’s usually late enough in the season that it doesn’t harm your tree.
Strategy 2: Remove the Webs
In small trees, the most effective solution can be to physically remove the webbing with a shovel, rake, or even a big stick. In larger trees, you can also prune out the affected branches. Throw the nests in the trash.
Even if you can’t completely remove the nests, don’t worry. Simply damaging them and opening up a hole is enough to allow birds or beneficial insects to get rid of the pests for you.
Strategy 3: Encourage Beneficial Insects
Several species of insects, including a number of tiny wasps, attack and kill webworms for you. Encourage beneficial insects by planting sunflowers or other plants in the daisy family in your yard. Or purchase beneficial wasps from an online supplier.
Strategy 4: Use Bt
A bacterium called Bt infects and kills many species of caterpillars, including fall webworms. A natural caterpillar disease, Bt won’t cause damage to plants, people, or pets. Bt is most effective if you can break a hole in the webbing to spray the disease onto the pests. Note: Bt does affect the caterpillars of many butterflies.
Strategy 5: Spray with Neem
Neem is one of a host of organic insecticides available. This product is derived from a tropical tree and can be very effective at getting rid of pests. Note: While neem is organic, it will kill many beneficial insects, so spray with care.