What Should I Spray For Tent Caterpillars

Tent Caterpillars – How do I get rid of tent caterpillars?

Wizzie Brown contributed to this article. Tent caterpillars attack a variety of broadleaf trees and shrubs, causing unattractive webs, or tents, to appear on the leaves. When their populations reach a critical mass, the caterpillars can defoliate trees, causing them to develop more slowly. They prey on ornamental and fruit trees, among other things. Early and correct identification of tent caterpillars, knowing their life cycle, and the use of suitable cultural or chemical management strategies are all essential for their eradication from the environment.

The eastern tent caterpillar, Malacosoma americanum, is the most troublesome of the four.

Life Cycle

Female moths lay their egg masses on tree trunks or tiny twigs throughout the late spring to early summer period (Fig. 1). The females of all Texas species, with the exception of the Sonoran tent caterpillar, utilize spumaline, a sticky, foamy substance, to “glue” the eggs to the bark or twigs of trees and shrubs. The spumaline also functions as a protective shell surrounding the egg mass, providing a firm, durable surface. During the majority of the summer, fall, and winter, egg masses linger on the branches of the trees.

  1. Eastern and western tent caterpillars begin feeding on these fresh leaves within a few days of their appearance.
  2. In most cases, the web is situated in the crotch of tiny limbs (Fig.
  3. Because the larvae wander away from their tents to feed on leaves, harm can occur even if the web is located a long distance away from the tents.
  4. These enormous, noticeable webs are created by the eastern and western tent caterpillars.
  5. The larvae molt, or lose their skin, multiple times throughout their development.
  6. The color pattern can also alter from instar to instar depending on the species.
  7. 3).
  8. Between feedings, dozens of caterpillars may assemble on these mats to wait for their next meal.
  9. Protected areas like as the web, under the bark, among dead plant material on the ground, within a curled leaf, or under the eaves of homes are all common locations for spiders to hide.
  10. Generally speaking, cocoons are loosely made of silk with a white or yellowish crystalline component dispersed throughout the whole thing.
  11. Tent caterpillars in their adult form are brown and yellowish moths with two diagonal patterns on the front wings of their bodies (Fig.

4). Their wingspans are around 1 inch in length. They are drawn to lights, like do other moths. A single generation of tent caterpillars occurs once a year in all species. Adults only survive for a few days, during which time they mate, lay eggs, and do not consume any food.


Tent caterpillars in its infancy are brightly colored and grow to be approximately 134 inches long when fully grown. The only lengthy hairs on their body are found around the sides and on the back. Individual species may be distinguished by the colors and patterns on their larvae. If you come across tents with larvae that do not fit the descriptions in Table 1, it is most likely that they are autumn webworm tents. Fall webworms may construct tents throughout the late summer and fall and can have numerous generations per year, depending on the species.


The degree of defoliation, unattractive webs, and nuisance caused by the caterpillars should be taken into consideration when developing a management strategy. It is possible that you may need to utilize a combination of cultural and chemical procedures to achieve the optimum results. Control over one’s culture. During winter pruning, look for egg masses, which show as swellings on tiny, naked branches and are a sign of infestation. When trees are pruned, the tent caterpillar eggs are frequently removed before they develop.

  • When you discover spider webs on twigs in the spring, prune them as soon as you notice them.
  • It is not suggested to burn the web or caterpillars since it is quite dangerous.
  • Remove the dead caterpillars from the ground and dispose of them.
  • Beneficial insects can help to lower the number of tent caterpillars.
  • Trichogramma species prey on the eggs of tent caterpillars.
  • Control through chemical means.
  • The use of insecticide is pointless if the tent caterpillars have been allowed to feed and develop to completion.

Tents are weather-resistant and will remain in the tree for an extended period of time until they are removed.

Early morning or late evening applications are recommended in order to concentrate the spray on the tents when the caterpillars cluster.

The species that may be sprayed with these oils will be listed on the label of the product.

Some organically generated goods contain active substances such as Bacillus thuringiensis (Bt)varietykurstaki, spinosad, or insecticidal soap, which are all derived from bacteria.

In order for the Bt kurstaki and spinosad to be taken up and consumed by the caterpillars, spray the plant well before applying the substance to the leaves.

Contact-kill insecticides such as insecticidal soap must be applied directly to the caterpillars in order for them to be killed.

Some of these formulations operate when they come into direct contact with the pest, while others may have an oil-based component that is comparable to horticultural (petroleum-based) oils in their composition.

There are several long-lasting, synthetic pesticide solutions available that give quicker and longer-lasting control than most plant-derived insecticides while also working on all phases of the caterpillar’s life cycle.

Bifenthrin, cyfluthrin, esfenvalerate, fluvalinate, permethrin, lambda-cyhalothrin, indoxacarb, acephate, and carbaryl are all active chemicals to search for in a pesticide formulation.

Pesticide users are accountable for the impact pesticides have on their own plants or home goods, as well as any difficulties that may arise as a result of pesticide drift from their own properties to the properties or plants of their neighbors.

Also prone to change are the regulations governing the use of insecticides and pesticides. Always read and carefully follow the instructions on the product label for the most dependable instructions.


The author would like to express his gratitude to Bart Drees, Glen Moore, and Kim Schofield for their contributions to the review of this article. Bart Drees provided all of the photographs. Download a printer-friendly version of this publication by clicking on the following link: Caterpillars of the Tent »See more details about Gardening and Landscaping» Do you have a question – or do you require the assistance of an expert? Make contact with the appropriate county office.

tent caterpillar control and treatments for the yard home and garden

Tent caterpillars are a very busy pest that may be found throughout the year. They have voracious appetites and will consume nearly any plant they come upon. Their nests are unattractive, their feeding habits are detrimental to plants, and they quickly move inside practically any building, creating a shambles in the process. Tent caterpillars are covered in full in this article, which will also explain how to control local infestations and nests on your property, as well as what products to use.

  • These animals are normally dark in appearance — primarily black – with a few lengthy, brightly colored stripes running down their backs.
  • It is possible that these lines be brown or yellow in color.
  • Even though they are scarcely detectable at this time, they will become more active when the surrounding plant life begins to produce their spring foliage in the coming months.
  • In the event that the host tree or shrub on which they originated does not supply sufficient food, the ants will travel to other adjacent native plants for sustenance.
  • Every evening after dark, the spiders will return to their host tree and begin spinning a “tent” that will continually expand to meet their ever-increasing size.
  • These tents, which are generally ugly, are white and silky in appearance and arise where the host tree’s limbs grow in two different directions at the same time.
  • These colonies will begin with several hundred caterpillars, and their “tents” can range in size from as tiny as a soccer ball to as huge as a compact automobile!

All of the tents will have been deserted, and caterpillars will be observed traveling in all directions, with no apparent purpose in mind.

In the course of their journey, they would frequently crawl on top of houses.

Once they have selected a comfortable area where they feel safe and sheltered, they will spin a cocoon and go through the process of transformation.

Females (adult moths) will search for a suitable host plant on which to lay eggs, and after they have located one, they will deposit 200-300 eggs on a branch that is kept together by a sticky material that is produced as part of the egg laying process.

When tent caterpillars feed, they may do a great deal of harm.

Because they will be unable to perform normal photosynthesis without their leaves, they will have to expend a significant amount of time and energy growing new leaves to replace those that have been lost, and as a result, they will be significantly more vulnerable to other problems such as disease and parasites.

Furthermore, caterpillar droppings will be found below host plants and will create a sloppy mess on automobiles, homes, lawn chairs, and other items of furniture.

They can be found under any host plant and can become quite a nuisance if the local population is in large numbers and consuming the droppings.

Their excrement is acidic, and it will “eat” through almost any type of car finish, causing it to rot.

In proportion to the size of each individual caterpillar, the colony will expand the size of their “tent.” Though caterpillars start each season small and barely noticeable, they will grow to be over 2 inches in length and the nest “tent” will have to made bigger to accommodate each individual’s larger size.

  1. Don’t be surprised to find nests the size of a basketball or larger.
  2. Trees in which nesting is successful will tend to attract more from year to year as previous generations will instinctively know a good host plant.
  3. And if the damage, droppings, or unsightliness of their nests isn’t enough to make these insects a bona fide nuisance, their annual migration surely will.
  4. Once larvae have had enough to eat, they will start to leave the main nest in search of a good location where they can undergo metamorphosis.
  5. They like to choose secure and discreet locations for this change and seem to like man made structures just as much as any tree.
  6. The migrating larva will be out in great numbers during this time traveling in all directions from the main nest and if they encounter a home or other structure, chances are they will try to make it their home for the next month.
  7. In fact many homes will actually get invaded each yearif they are located in the migration path of tent caterpillars.

Fortunately, there are some very effective treatment options for controlling tent caterpillars.

This concentrate is basically a concentrated bacteria.

Thuricide can be sprayed on any plant, vegetable or fruit without posing a hazard and is a good preventive material to use – especially if you are treating before they arrive.

Retreat every 2 weeks.

Another approach is to apply a band ofINSECT GLUEaround the trunk of any targeted tree.

Make the band at least 1 inch wide; a tub of Insect glue is enough to treat 3-5 large trees.

This is an excellent protective treatment that will stop all insects from accessing beneficial plants.

There are a few organic products approved and certified for caterpillars but we have foundBT GARDEN DUSTandMULTI PURPOSE INSECT KILLERto perform the best.

Feeding caterpillars will die within 7-10 days of eating plants and foliage with BT dust.

If you have tall trees, dusting will be ruled out as an option.

While used on organic gardens (fruits and vegetables), this fast-acting concentrate is permitted for usage.

Use no more than 800 sq/ft of foliage to apply the mixture, which should include 5 oz per gallon of water.

The use of this concentrate on food crops is not recommended; nonetheless, it is wonderful for any tree, shrub, or even for the home’s landscape.

Bifen treatments can last for up to a month and can effectively eliminate virtually every bug that comes into contact with them on treated surfaces.

Because caterpillars have a lot of hair, you need use SPREADER STICKER in your tank mix.

When spraying plants, it is often difficult to achieve adequate coverage due to the fact that leaves have undersides that are resistant to direct spray.

Furthermore, it will increase the direct effect that Bifen has on the caterpillars that have been targeted.

If you have a large number of nests that you wish to cure immediately, you have two alternatives.

See also:  How To Make A Indian Pillow Tent

This might be difficult due to the fact that most nests will be located high up the tree and the webbing can be fairly thick.

This will ensure that all caterpillars have returned to the nest and are laying eggs inside of it.

Make three or four holes in their tent using a stick or pole.

Once the access holes have been created, spray the nest with the solution that you have prepared.

HORNET KILLER is another product that may be used as a direct therapy.

Prior to spraying the tents, you will still need to poke 3-4 holes in each of them, but after the entry points have been created, soak the nest down for an efficient death.

Remember, this is only effective for treating nests directly; it is not recommended for spraying over leaves, since this will cause harm to the tree, shrub, or other plant being treated.

Fortunately, there are two products that will both prevent them from entering and kill them if they do attempt to do so.

This concentrate, when mixed with water, may be put to the foundation and up the side of the house a few feet to create a barrier that caterpillars will be unable to crawl through.

Cypermethrin is extremely irritating to caterpillars and will kill those that are present while also leaving a strong residue to deter future infestations.

When caterpillars are active, apply 1 gallon per 500 sq/ft of surface area and retreat once every 2 weeks while they are active.

However, FS MP AEROSOL should be used in locations where a liquid cannot be used.

It, too, may be used along baseboards, around window frames, and even higher up on the ceiling by way of crown molding.

If you don’t act quickly, you may expect to observe a large number of adult moths hatching out of pupa cocoons in the first 1-2 months after the first invasion.

Our regular sprayer has a maximum reach of approximately 15 feet and is adequate for small applications.

It is capable of reaching distances of up to 30 feet and is fully portable due to the fact that it operates by pumping out a mixed solution from a 5 gallon bucket.

These will spray as far as your garden hose is capable of reaching.

However, once they begin their spring feeding, their chewing and devouring may cause significant damage and stress to a wide variety of trees and plants.

With any hope, this will prevent them from entering the structure.

Treat early in the season to keep tent caterpillar populations under control; kill as many as you can while the season is in full bloom else you will have that many more tent caterpillars to cope with the next year if you do not treat early in the season.

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How To Get Rid Of Tent Caterpillars

This post may contain affiliate links; please see my full disclosure policy for more information. Because I am an Amazon Associate, I receive money when people make eligible purchases. You’ve come to this location because tent caterpillars are devouring your trees, correct? No surprise that caterpillars are a major issue for trees, and especially fruit trees, in the United States. A huge nest of tent caterpillars may quickly defoliate your trees, but don’t worry, I have a really simple method for killing the caterpillars in your trees that takes just ONE simple thing that you probably already have in your house right now.

  • Healthy trees will simply regrow a new set of leaves when they are damaged.
  • However, if your trees are young, the stress of losing their leaves might cause them to develop more slowly or, in the worst case scenario, cause them to die.
  • We had a significant infestation of tent caterpillars the first year they started to produce properly, which was really frustrating.
  • That year, we were unable to harvest our apple crop, and I vowed to myself that this would never happen again.

To control a pest in your garden you need to understand its life-cycle.

Tent caterpillars can be found in all three of the following kinds, depending on your geographic location. Despite the fact that they seem different from one another, they both cause the same sort of damage to your trees. Contrary to the fall webworm, which may be spotted in trees throughout the late summer and early fall, these are not the same thing.

Eastern Tent Caterpillars

In color, the Eastern Tent Caterpillars are mostly black, with a white stripe running down the middle of their back and a row of bright blue dots on either side of their body. Cherry, apple, and crabapple trees are among their favorite food sources, although they will also consume other types of trees such as shade trees.

Western Tent Caterpillars

The Western Tent Caterpillar is a yellowish-brown caterpillar with a series of blue and orange dots running down its back. They eat fruit from trees such as cherry, apple, plum, willow, birch, poplar, and oak.

Forest Tent Caterpillars

The Forest Tent Caterpillar has a similar appearance to the Eastern Tent Caterpillar in terms of coloration. They are black with white keyhole-shaped markings running down the rear of their bodies. Unlike other tent caterpillars, which build nests in the forks of trees, these caterpillars form a silk mat along the surface of the branches they feed on. Tent caterpillars are one of the most gregarious forms of caterpillars, and they are members of the moth family Lasiocampidae. The eastern tent caterpillar is the most common variation seen in our region, and it is the most common variety in the world.

  1. These eggs develop swiftly, and by three weeks, the caterpillars will have fully developed into butterflies.
  2. Their hatching is timed to coincide with the regrowth of the trees’ leaves.
  3. These are initially extremely little, but as the caterpillars develop in size, they become bigger.
  4. Look very closely at the forks of the tree branches, since this is where they prefer to make their nests.
  5. Typically, this occurs soon before sunrise, throughout the middle of the day, and shortly after sunset.
  6. They then return to their nest once they have done feasting.
  7. In the final stage of the caterpillar’s existence, they separate from one another in order to select a suitable location for forming their individual cocoon.
  8. They are nocturnal, and you have most certainly seen these medium-sized brown moths fluttering around in the dark throughout the night.

They reproduce quickly after hatching, and the females die within a few days of depositing her clutch of eggs. Because you now understand the tent caterpillar’s life cycle, it will be much easier to maintain control.

How To Kill Tent Caterpillars In Your Trees

Tent caterpillar nests are frequently destroyed by burning them with a tiny propane torch, which is highly effective. This is the method I learnt as a child, and I’ve witnessed many others use it to eliminate caterpillar nests. However, there are several drawbacks to this approach.

  1. Caution should be exercised while burning caterpillar nests since it may cause harm to your tree and leave huge, unsightly black patches behind. This is something I’ve done in the past, and it is quite unsightly! It is possible to get around this by cutting the branch after it has been burnt. However, this causes further harm to the tree, and what if your nest is located at a high point in the tree or on a huge branch? You really don’t want to inflict any serious damage to your trees, do you? Indeed, isn’t that what you’re attempting to protect them from in the first place
  2. When the weather is windy, it might also be difficult to burn the nest with a torch since little torches are readily blown out of their holders. If the nest is located at a high point in your tree, going up to it or using a ladder is not the safest option when using a torch

So the really easy way that we came up with for killing tent caterpillars is simplyvegetable oil!

It’s really that straightforward! The understanding of the caterpillar’s life cycle is essential to make this work. You must wait until all of the caterpillars are in the nest at the same time before spraying the nest well with vegetable oil. Because insects breathe via their skin, this method is effective. When they are covered with oil, they are unable to breathe and die within minutes. However, because I’m a frugal person, I keep the wasted oil from our deep fryer, which I then use in this recipe.

I really like the heavy-duty spray bottles that I’ve been using.

I frequently use them not just to make an oil spray for caterpillars, but also to apply combinations of tea tree oil or liquid fertilizers as a foliar spray on the leaves of plants.

The Benefits Of Using Vegetable Oil

  1. It kills the caterpillars swiftly and does not leave any unsightly black patches on the leaves of your plants. If left to its own devices, the nest will disintegrate and collapse in a short period of time. It is also lot simpler to spray the oil on the nest that is higher up in your tree than it is to attempt to burn them with a torch.

Would you like to see just how well this works?

Watch my video to see how simple it is to use this approach of controlling caterpillars in my fruit trees in your own yard. Isn’t it great when you can find simple and safe techniques to keep pests under control in your garden?

Other Ways To Control Tent Caterpillars

While spraying the nests with vegetable oil is my preferred method of controlling these pests, it is no longer effective once they have outgrown the communal nest. However, there are still simple ways to get rid of tent caterpillars on your trees and in your yard. Read on for more information.

How To Get Rid Of Tent Caterpillars With Dish Soap

Another quick and simple method for getting rid of caterpillars is to spray them with dish detergent. The key to making a dish soap spray effective is to avoid allowing the soap to froth excessively. Fill the spray container almost to the brim with water, then add 1-2 teaspoons of dish soap per gallon of water and shake well. After that, finish topping off the water supply. Give the sprayer a slight shake to ensure that all of the soap is included. This helps to keep the soap suspended in the water rather than having it float to the surface as bubbles.

Use BTK Spray

The best alternative if your trees are being devoured by tent caterpillars but you can’t discover a nest to remove is to use an organic BTK (Bacillus thuringiensis) spray, which is safe and effective.

This naturally occurring bacterium is only harmful to caterpillars, and it is completely safe to use around birds and bees. Simply spray BTK on the leaves of your trees, and the caterpillars will be killed as a result of eating the poison.

Download a tip sheet to help you remember how to spot tent caterpillars in your garden and control them safely!

Do you have a cucumber beetle infestation in your yard or garden? See how I got rid of them in a quick and simple manner! A homeschooling parent of six children, Kim Mills lives on an urban farmstead in the province of Ontario, Canada. She likes blogging at Homestead Acres, where she shares money-saving strategies as well as information on how to cultivate and store your own food.

How to Get Rid of Tent Caterpillars

Tent caterpillars are the larvae of various moth and butterfly species (mentioned below), which are referred to as a group by their common name. These caterpillars, which are found throughout most of the United States and Canada, reproduce quickly and have the ability to defoliate a significant number of deciduous trees and shrubs in a short period of time. These pests are frequently seen on wayside trees and in abandoned orchards. Aside from defoliation, the larvae build big unattractive webs, or tents, in the crotches of tree limbs, which are difficult to remove.

See also:  How To Winterize Coleman Tent Trailer

Despite the fact that tent damage is ugly, infestations of insects seldom endanger the life of trees.


The Eastern Tent Caterpillar (Malacosoma americanum) is a species of caterpillar that may be found east of the Rocky Mountains and north into southern Canada. In their full developed state, caterpillars are sparsely hairy and black in appearance, with a row of pale blue markings on either side of their bodies. They may be distinguished by a white stripe running down the middle of their backs, which helps to identify them. Adults are reddish brown moths that are 1-1/2 inches in length and have two white stripes running diagonally across each forewing.

  1. The Western Tent Caterpillar (Malacosoma californicum) is a pest that may be found in the northern and western regions of the United States as well as in adjacent Canadian territory.
  2. Approximately 1-1/2 inches in length, adult moths are orange-brown in color with two faint yellow lines on the underside of the wings.
  3. Malocsoma disstria is a forest tent caterpillar that may be found across the United States and Canada anywhere hardwoods can be found in the forest.
  4. americanum are similar in appearance to the adult, but instead of a solid line running down their back, they have a series of keyhole-shaped white dots.
  5. Wild cherry, aspen, maple, oak, and hawthorn are among the plants that serve as hosts.
  6. Webworms are known to feed on over 85 different types of trees and are found across North America and Mexico.
  7. One-inch-long caterpillars are coated with long hairs and range in color from yellow to green, with a black stripe along the back and a yellow stripe on each side of the body.

The color of their heads is either red or black. Adult moths (1 inch in length) are pure white in color with black markings on the wings, which are characteristic of the species.

Life Cycle

The egg stage is where the majority of tent caterpillar species overwinter. Egg masses ranging in color from dark brown to gray and holding 150 to 400 eggs are adhered to the short twigs of trees and bushes. Hatching takes occur around the time when leaf buds begin to open, which is normally in the early spring months. They are social creatures who quickly build silken tents, which they use as a haven during the early morning and evening hours, as well as during rainy spells, to protect themselves from the elements.

The larvae reach full maturity around six weeks after hatching and five instars following that time period (up to 2 inches long, sparsely hairy).

Adult moths emerge around two weeks later and deposit the overwintering eggs within a short period of time.

Note: When larvae begin to travel to sheltered regions in order to pupate, they can become a nuisance.

How to Control

  1. Prevent the larvae from starting to eat by scraping off and discarding overwintering egg masses and tearing the protective tents out by hand before they start to feed. With this method, you may restrict caterpillar mobility and deny them access to eating locations. Sticky Tree Bands or Tree Tanglefoot Pest Barrier are two options for preventing pest infestations. The naturally occurring soil-dwelling bacteriumBacillus thuringiensis, often known as Bt-kurstaki, is highly powerful against all species of inch worms. At the first indication of damage, use a spray that is simple to apply to knock out the worms and safeguard the foliage. It is safe to use BTKsprays near dogs and children since they do not damage honey bees or birds
  2. Spinosad, a biological substance developed from fermentation, is also extremely useful in a variety of applications. In fact, it’s the active ingredient in Monterey Garden Insect Spray, a product that has been classified as organic by the United States Department of Agriculture’s National Organic Program and listed for organic use by the Organic Materials Review Institute
  3. AzaMaxcontains azadirachtin, which is the key insecticidal ingredient found in neem oil. This very powerful spray interferes with the growth and development of nuisance insects while also acting as a repellant and anti-feedant. In addition to being non-toxic to honey bees and many other helpful insects, it should only be used as a last resort for dealing with bug infestations. Natural pesticides, which are derived from plants that contain insecticidal qualities, have less adverse side effects than synthetic chemicals and degrade more quickly in the environment.

Note: Although more than 80 species of predators and parasites have been identified in the United States, none of them are now available for purchase on the market. During the majority of the year, these insects serve a crucial role in keeping pest populations under control. As a result, extreme caution must be exercised while spraying pesticides in order to avoid causing harm to these important species.

What Chemical Kills Tent Caterpillars?

To defend themselves from predators while consuming the leaves of trees, roses, and other plants, tent caterpillars construct silky, tent-like homes for themselves. These pests are mostly found in the Lasiocampidae family, with the Western tent caterpillar (Malacosoma californicum) being the most frequent, followed by the Pacific tent caterpillar (Malacosoma constrictum) and forest tent caterpillar (Malacosoma disstria) being the least common. The majority of people construct tents out of forked branches.

Eventually, they build cocoons and emerge as adults in the middle of summer.


According to the California Statewide Integrated Pest Management website, pesticides containing the active chemical lambda-cyhalothrin are efficient against tent caterpillars, however they are extremely hazardous to honeybees due to their high toxicity. The chemical is extremely hazardous to aquatic species, as well as to helpful insects in the environment. Connect the hose end of the ready-to-use pesticide to the faucet and turn the dial to the “off” position before turning on the water faucet.

Spray the upper and bottom surfaces of the foliage with the spray, starting at the farthest end of the area to be treated and working your way in. When fresh caterpillars hatch, repeat the process as many times as necessary.


Keep children and pets away from the treated area until it has dried completely. Instead of using insecticides, try trimming or cutting tents from the afflicted plants and destroying them as a preventative measure. Look for clumps of gray to dark-brown eggs that resemble plastic foam in appearance. Scraping the eggs off the bark or from around twigs can help to lessen the likelihood of an infestation occurring greatly. Non-chemical pesticides such as Bacillus thuringiensis subspecies kurstaki (Btk) are also available as an alternative to chemical pesticides.

Identify and Control Tent Caterpillars

In the spring, several different varieties of caterpillars weave tentlike webs in the branches of trees and shrubs. Tent caterpillars are a kind of caterpillars that spin ugly webs and eat plant leaves, thus the name. The protective webs expand in tandem with the number of hungry larvae. They may prefer small fruit trees such as cherries and crabapples, but they may attack a wide variety of other trees and ornamental shrubs, depending on the species in question. Plants that have been defoliated are weaker and more prone to attack by various insect pests and diseases.

  • Their black bodies are covered with fine, reddish hairs.
  • From a distance, other species appear to be similar, but their markings differ.
  • Their eggs overwinter in lustrous, black egg masses that ring twigs and are protected from the elements.
  • The bugs congregate outside the tents to feast on the food.
  • Management: Tent caterpillar control is most effective when applied early in the spring when caterpillars and webs are tiny.
  • GardenTech ® brand provides very efficient solutions for smaller trees and shrubs that kill tent caterpillars on contact and continue to protect for up to three months:
  • For treating shrubs and small trees completely, such as to guard them against developing caterpillars and to treat active infestations, Sevin ®Insect Killer Concentrateis an excellent choice. Use of the chemical in conjunction with a pump-style sprayer results in extensive coverage and direct treatment of webs and their surrounding regions. Make sure to completely cover all plant surfaces, giving particular care to forks where branches come together. Sevin ®Insect Killer Ready to Spray makes it easier to treat tent caterpillars before and after their tents form, saving you time and money. The tool fits to a standard garden hose and automatically measures and mixes the solution as you spray. Cover all plant surfaces completely with the product, and treat tents immediately. Caterpillars come into touch with the spray as they enter and exit the feeding chamber.

Prevent overwintering egg masses from forming on trees and shrubs by pruning them before they hatch. Webs should be removed on chilly or wet days, when caterpillars are more likely to be hiding within. Reading product labels and following the directions exactly are essential, especially when it comes to pre-harvest intervals for fruits and other culinary crops.

GardenTech is a trademark of Gulfstream Home and Garden, Inc., which is owned by Gulfstream Home and Garden. Tessenderlo Kerley, Inc. owns the trademark Sevin, which is a registered trademark of the company. CREDIT FOR THE PHOTO:

  • “Eastern Tent Caterpillar (Malacosoma americanum)” by Ryan Hodnett is available under a Creative Commons Attribution-ShareAlike 2.0 license, and “Eastern Tent Caterpillar Moth (Malacosoma americana)” by Aaron Carlson is licensed under a Creative Commons Attribution-ShareAlike 2.0 license. “Eastern tent caterpillar (Malacosoma americanum)” by Whitney Cranshaw at Colorado State University (Bugwood.org) is licensed under CC BY-SA 2.0
  • “Eastern tent caterpillar (Malacosoma americanum)” by Whitney Cranshaw at Colorado State University (Bugwood.org) is licensed under CC BY-SA 3.0
  • “Eastern tent caterpillar (Malacosoma americanum)” by Whitney Cranshaw at Colorado

UC Management Guidelines for Tent Caterpillars on Plum

During the winter, tent caterpillars remain in the egg stage, and the eggs hatch into caterpillars in the spring and early summer. In addition to being hairy and dull golden brown, the western tent caterpillar has a row of blue dots close to orange spots on the top of its body. The woodland tent caterpillar is dark gray in color, sparsely hairy, and striped on the shoulder and side with thin yellow-brown stripes that are divided by a large blue lateral stripe. The most recognizable characteristic of this species is a pattern of white diamond or keyhole-shaped spots that run around the back of the animal.


Damage caused by tent caterpillars may be serious on individual trees. From April to June western tent caterpillars build large silken tents over leaves on which they feed. Forest tent caterpillars build mats of webbing rather than tents. They forage in all directions from these mats but return to the colony when not feeding. Tent caterpillars do not eat leaf veins.


Tent caterpillar populations tend to be confined in a few trees spread around the orchard, rather than in large numbers over the whole orchard. Treatment is only necessary on an as-needed basis, and it can be restricted to a small section of the orchard. Methods that are organically acceptable Bacillus thuringiensis is a kind of bacteria. Spraying and trimming out infestations are both appropriate organic management techniques. Decisions Regarding Treatment Cut off and remove contaminated twigs on tiny trees to prevent them from spreading.

If pesticide treatments are required, small-scale applications on individual trees and branches are usually sufficient to achieve the desired results.

The use of a wetting chemical to facilitate the penetration of the pesticide into the webbing results in improved control of the insect.

Common name Amount to Use** R.E.I.+ P.H.I.+
(trade name) (conc.) (dilute) (hours) (days)

The following materials are listed in order of usefulness in an IPM program, taking into account efficacy,impact on natural enemies and honey bees, andimpact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
(various products) Label rates 4
COMMENTS: Most effective on small caterpillars. Does not destroy natural enemies.
B. DIAZINON* 50 WP 3 lb 1 lb 24 21
4EC 3 pt 1 pt 24 21
COMMENTS: Avoid drift and runoff into surface waters. Where plums are grown near waterways, do not use diazinon.
** For dilute applications, rate is per 100 gal water to be applied in 300–500 gal water/acre, according to label; for concentrate applications, use 80–100 gal water/acre, or lower if the label allows.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
* Permit required from county agricultural commissioner for purchase or use.
Acceptable for use on organically grown produce.
Not recommended or not on label.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at


UC IPM Pest Management Guidelines:Plum UC ANR Publication3462 Insects and MitesW. J. Bentley, UC IPM Program, Kearney Agricultural Center, ParlierK. R. Day, UC Cooperative Extension, Tulare CountyAcknowledgment for contributions to Insects and Mites:R. E. Rice, Kearney Agricultural Center, ParlierTop of page

How to Identify and Control Tent Caterpillars

No other insect strikes horror into my heart quite like a squirming, crawling mass of tent caterpillars. Call me theatrical, but there isn’t another bug that can do that to me. It’s not because of the harm they inflict to plants, but rather because their nests appear like something out of a horror film, which is understandable. Isn’t it true that a single caterpillar is kind of adorable? Some of them even have marks that resemble a smiley face on their faces. But when you’re in a bunch. yuck!

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A significant infestation can result in swarms of them creeping down the road and sidewalks at the same time.

‘Ugh!’ I say again.

In spite of the fact that I am totally disgusted by them – surprise! – they are still one of my favorite things to see. I’m also going to make a case for why you should, at the very least, leave them alone in this situation. Here’s what we’ll be talking about.

What Are Tent Caterpillars?

The phrase “tent caterpillar” refers to the larvae of all species of moths belonging to the genus Malacosoma, which includes all forms of tent caterpillars. There are around 26 species worldwide, with six of those found in the United States. One thing that they all have in common is that during the spring, the caterpillars build big communal nests on trees out of silken threads, which are then consumed by the birds. Some make a type of “home base” that they leave and return to throughout the day, and others build tents continually as they walk around the tree’s circumference at night.

  1. californicum, also known as the Western tent caterpillar, M.
  2. disstria, also known as the forest tent caterpillar, are the most prevalent in the United States.
  3. californicum is a species of fungus that may be found in the western United States, southwestern Canada, and northern Mexico.
  4. The majority of the time, they have dark blue or black heads, and their bodies are green, black, orange, or blue, or a combination of these hues, with fine hairs (setae) covering their bodies in general.
  5. They can grow to be up to two inches in length.
  6. M.
  7. The larvae are black with a white dorsal stripe and blue specks on the back, and they are coated in small reddish hairs on the rest of their bodies.

Fruit trees such as cherry, peach, and plum, as well as witch hazel and hardwoods such as ash, birch, hawthorn, maple, oak, and willow, are among the trees that these caterpillars like.

disstriais may be found all throughout the continental United States and southern Canada.

They have delicate, light hairs covering their bodies.

In contrast to the other two species listed above, this species does not establish a home base tent that it uses to keep close to.

They may also tie up leaves with silk to construct small protected pods, which they may then eat.

tigris), which may be found in the western United States, and the Southwest tent caterpillar (M.

Tent caterpillars are all fuzzy rather than smooth, and they do not have the big tufts of hair at either end of their bodies as some other caterpillars do.

Because they all look different and there isn’t a defining physical characteristic that distinguishes them from other caterpillars, it’s easiest to identify tent caterpillars in general by the characteristic tents they make and the damage they cause to trees, rather than by their specific appearance or physical characteristics.

  1. In the spring, the nests are tiny and compact to begin with.
  2. They are likewise creamy white in the beginning of the season, but as they full with feces, their color progressively darkens to a brown shade.
  3. As they crawl up the branches of the trees, these parasites consume a lot of vegetation, which they chew up as they go.
  4. The caterpillars, as they travel around the tree, leave a silken string in their wake, which is quite interesting to observe.
  5. However, if the caterpillar descends a branch that does not have much food on it, the caterpillar will cut the thread, preventing subsequent caterpillars from wasting their time searching for food there.
  6. They’re true team players, you know!
  7. Webworms (Hyphantria cunea) are sometimes lumped together with tent caterpillars, however they are two completely separate insects.
  8. In addition, webworms are more active in the summer and fall than they are in the spring.

Lymantria dispar dispar is the gypsy moth. These areLymantria dispar dispar, which is a distinct species of moth from a different genus entirely.

Biology and Life Cycle

This pest reproduces just once a year, and it has only one generation every year (thank goodness). The eggs are placed in large clusters around branches throughout the summer months and are held in place by a sticky material that the birds produce called spumaline. The masses have a brown tinge to them, and the eggs are left in place on the tree so that they can overwinter there. The caterpillars emerge from their eggs in the spring and cluster on a tree to build a communal nest, where they spend the evenings and inclement weather before emerging to feast on the foliage.

As the caterpillars increase in size, they begin to munch on the leaves of trees, eventually defoliating the entire tree when in big enough numbers.

The moths emerge from their cocoons a few weeks after they have formed them in order to mate.

Adult moths do not consume any food at all.

Organic Control Methods

Many specialists now advise simply letting these wigglers alone, as they have in the past. An infestation will not harm a tree unless the tree is already stressed by disease or other environmental stresses such as drought, in which case it will die. Even if the caterpillars fully defoliate a tree, the tree should be able to recover once the pests have fled the scene. Furthermore, these insects are a vital component of the natural ecosystem, and they are preyed upon by a variety of natural predators.

  1. Having said that, there are a few reasons why you’ll want to get rid of these pesky insects.
  2. This is due to the fact that defoliation might cause the tree’s development or productivity to be stunted for the duration of the growing season.
  3. They are also the pests that you will most likely want to control or eradicate because they prey on trees that are economically valuable.
  4. Second, trees that are already stressed due to drought, disease, or other pests may not be able to endure an infestation of the pests mentioned above.
  5. If you have horses, you have still another incentive to bring an infestation under control.
  6. They subsequently spread throughout their bodies, puncturing the intestinal wall and transporting inside bacteria to areas where it shouldn’t be.
  7. Horses that are not pregnant might also ingest the insects and have eye or heart problems as a result.

If you, your kid, or your pet ingests the insects, keep in mind that the fine hairs on their bodies have been observed to irritate the skin of certain individuals.

Finally, if they are simply giving you the heebie-jeebies, you may choose to have them taken away.

Their frass, commonly known as excrement, is a valuable source of fertilizer.

After being defoliated, the majority of trees grow back with more leaves than they had before.

So, despite the fact that I feel goosebumps just thinking about them, I choose to allow them to be in my yard — a purposeful tactic known as “tolerance” in scientific circles.

Final point: if you don’t find the nests until the beginning of summer, there is no need to destroy them in order to attempt and manage the pest population.

The caterpillars are already fully adult at that stage, and they will be going on in the near future. However, if you do not like the appearance of the spider webs, you are welcome to brush them away.

Physical Control

The most effective way to get a handle on these pests is to physically remove them from your home. There are a variety of approaches that may be used to accomplish this. Trim away the branches that are most highly infected, as long as the nest is not in a major branch or on a portion of the tree’s trunk. Additionally, you may use a broom to sweep out the nests and place them on a sheet before bagging and disposing of the bugs. Performing the sweeping and pruning at night, early in the morning, or after a rainfall will ensure that you are eliminating all of the caterpillars that are resting or seeking shelter, rather than simply the caterpillar nest itself.

Their flames will spread throughout the tree as they separate themselves from the trunk and become blazing flags flying in the breeze.

During the winter, prune out or remove any egg masses that have formed by scraping them off with a knife.

Biological Control

A large number of natural enemies attack these caterpillars. Put them to work for you to assist you in keeping an infestation under control. Apart from attracting bird visitors, you may also attract ladybugs, tachinid flies, and parasitic wasps to your garden by planting them in the Hyposter, Cotesia, and Bracongenera, as well as the Edovum puttleri. Spiders, stink bugs, army bugs, paper wasps, assassin bugs, and lacewings are some of the predators that prey on these insects. Predatory insects are available for purchase and introduction into your garden if you do not already have a large number of them.

Bacillus thuringiensiskurstaki (Btk) is efficient against little caterpillars under an inch in length, but it becomes less effective as the caterpillars grow in size.

Organic Pesticides

Preventing a caterpillar infestation from forming in the first place can be accomplished by spraying the egg masses with a dormant oil during the winter months. The eggs will be smothered as a result of this. Because the timing of application and the suggested amount vary depending on the plant, it is important to precisely follow the manufacturer’s instructions. Spinosad is a very powerful pesticide that has the extra virtue of not being toxic to the vast majority of beneficial insects on the planet.

Monterey Garden Insect Spray is a product manufactured by Monterey Garden Insect Spray.

For the last organic pesticide, insecticidal soap can be effective, but it must come into direct contact with the larvae in order to be effective.

Ensure that you follow the manufacturer’s recommendations for the exact type of tree you are spraying. Bonide Insecticidal Soap is a natural insecticide. In 12- and 32-ounce containers, Bonide offers a nice ready-to-use choice that can be purchased through Arbico Organics for a reasonable price.

Chemical Pesticide Control

We do not advocate using chemical pesticides to manage tent caterpillars since they are not a pest that normally causes catastrophic losses and because there are no insecticides that are especially aimed at tent caterpillars available. It is possible that doing so would harm the other beneficial insects in your garden, which will have long-term implications for the environment. You should also use great caution when eradicating any native insect populations, since doing so may have unforeseen and long-term consequences for the environment.

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