Call me dramatic, but no other pest squirms and squirms like tent caterpillars that terrify my heart.
It’s not because of the damage they do to plants, but because their nests look like something out of a horror movie. A caterpillar is kind of cute, isn’t it? Some of them even have markings that look like a happy face. But in a group…Bah!
Not just nests. The infestation is large, and many of them can crawl along streets and sidewalks. Have you stepped on a bunch of caterpillars? Double fly! I’ll help you learn how to get rid of Tent Caterphillars.
But despite what I just said they were pretty disgusted with them. Surprise! I would also argue why you should leave them alone. That’s what we’re going to discuss.
Table of Contents
About Tent Caterpillars?
Caterpillars is a general term that includes the larvae of all moths of the genus Malacosoma. There are about 26 species worldwide, 6 of which live in the United States.
What they all have in common is that in the spring, caterpillars build large communal nests on trees with silk thread.
Some create a sort of “base camp” that they leave and return during the day, while others constantly pitch their tents as they walk through the trees.
The most common borer in the United States is M. californicum, also known as western borer, American borer, eastern borer, and M. disstria, or forest borer.
M. californicum is found in the western United States, southwestern Canada, and northern Mexico. There are several subspecies, all of which may differ in appearance.
Usually they have dark blue or black heads, their bodies are green, black, orange, blue, or a mixture of these colors, and their bodies are covered with fine hairs (setae).
They always have a series of dots on their backs. They grow up to two centimeters long.
Host trees include aspen, willow, aspen, and mahogany.
M. americana lives in the eastern United States and southeastern Canada. The larvae are black with white stripes and blue spots on the back, and are covered with reddish fine hairs. Individuals grow to two centimeters in length.
These caterpillars tend to prefer fruit trees like cherries, peaches and plums, witch hazel, and hardwoods like ash, birch, hawthorn, maple, oak, and willow.
M. disstria is found in the continental United States and southern Canada. They are brown with light blue stripes and white keyhole spots on the back. They are covered with fine, light-colored hair.
This species prefers aspen, gum, and oak, but they can grow on almost any hardwood tree.
Unlike the other two above, this species does not form a family tent to stay nearby. Instead, groups of people roam the woods, forming smaller tents along the way. You can also wrap the leaves in silk to form small protective pods.
Less common are the Sonoran cat bug (M. tigris), which lives in the western United States, and the southwestern cat bug (M. incurva), which lives in New Mexico, Arizona, Nevada, and Utah.
All tent caterpillars are hairy, not smooth, and do not have the large tufts at the ends that some other caterpillars have.
They also have a single stripe, multiple stripes, or a series of broken spots on their bodies.
Since they all look different and have no obvious physical characteristics to distinguish them from other caterpillars, tent caterpillars are often easiest to identify by the unique tent they build and the damage they do to trees.
The nests they build are made of silk threads that protrude from their heads, and they usually form on the crotch of a branch.
Nests start small and compact in spring. As the seasons progress, the tent will gradually deteriorate with the wind and rain, becoming larger and more loosely woven.
They are also milky white early in the season, but gradually turn brown as the manure fills up.
By the way, if you imagine a tent made of silk, their nests are actually more like layers of silk hammocks.
These pests are voracious eaters, munching on leaves as they crawl along branches.
You’ll first notice leaves with ragged edges or deciduous branches, and in extreme cases, the entire tree can drop leaves.
Interestingly, when the caterpillars crawl the trees, they leave a thread behind.
If you find a good branch with large, succulent leaves, it will leave intact threads for its mates to follow for a nice meal.
But if it comes off a branch that doesn’t have much food, the caterpillar will cut the thread so other caterpillars don’t waste time looking for food there.
This means that they not only create living communities, but they also help each other find food. They are true team players!
Sometime in midsummer, the caterpillars fully mature and leave the nest to pupate, after which the filamentous nest falls apart.
Some people classify Hyphantria cunea as tentacles, but they are different insects. Networms build a loose nest at the end of a branch rather than at the crotch of the branch.
Networms are also more likely to be active in summer and fall than in spring.
Finally, to avoid confusion, since the larvae of both look similar, adult tent caterpillars are not gypsy moths.
These are Lymantria dispar dispar, another moth from a completely different genus.
This pest has only one generation per year (thank goodness).
In summer, the eggs are laid in groups around tree branches and are glued in place with a sticky substance called spumalin.
The lumps are brown and the eggs are left in place to overwinter on the tree.
Caterpillars hatch in the spring and gather in trees to form a communal nest, where they retreat to feed on leaves at night and in bad weather.
It takes about six weeks from hatching to cocooning on trees, buildings and fences.
As the caterpillars grow, they gnaw on leaves and, in large enough groups, may even defoliate entire leaves. Once they leave the nest and pupate on their own, they stop eating.
After a few weeks of cocooning, the moths begin to mate. Most moths of this breed are dark brown and have a wingspan of about two inches. Adult worms don’t eat at all.
Infestations typically occur every ten years for a year or two, before the moths move elsewhere or predators bring the numbers back.
How To Get Rid Of Tent Caterpillars By Organic Methods
These days, many experts advise leaving these wavers alone. Unless the tree is already stressed by disease or other environmental stressors such as drought, infestation will not kill it.
Even if the caterpillar completely defoliates the tree, it should recover after the pest has taken off.
Furthermore, these insects are an important part of the natural environment and have many natural enemies. Larvae and adults are a food source for dozens of species of birds, bats, lizards and other creatures.
However, there are several reasons why you can get rid of these pests.
First, if you’re relying on your tree for harvest, be sure to tackle the infestation unless you’re willing to give it up or the yield is lower than normal.
This is because fallen leaves can hinder the growth or performance of the tree during the growing season.
Because they tend to attack trees of economic value, such as B. fruit trees, caterpillars are often the most economically destructive of these pests and the ones you are most likely to want to control or eradicate.
Forest borers are a threat to sugar maples, so be careful when raising them.
Second, trees already stressed by drought, disease, or other pests may not be able to withstand infestation. If you don’t want to lose your poor tree, you need to give it a little extra help by getting rid of pests.
Another reason for pest control is that you have horses.
The brood may inadvertently eat the caterpillar, and the hair covering the larvae can shed in their digestive tract.
These hairs then travel through their bodies, puncturing the intestinal wall and carrying internal bacteria where they shouldn’t be.
This can wreak havoc, possibly causing them to miscarry or give birth to weak foals. Horses that are not pregnant can eat insects and develop eye or heart problems.
If you can’t get rid of the caterpillars, you may need to move the horse to a different location to graze for a while.
Be aware that the fine hairs on these pests have been reported to irritate the skin of some people, and if you, your children, or pets ingest these insects, the hairs may cause problems when penetrating the intestinal wall.
Finally, if they only give you Heebie-Jeebies, feel free to delete them.
However, I would like to remind you that they are an important food source for many animals and other insects. Their manure or poop is also a good source of fertilizer.
Also, trees and forests have another benefit besides extra food.
After defoliation, most trees bounce back more leaves than ever before. Although they are bare, bush plants get a lot of sun.
While I get chills just thinking about them, I choose to keep them in my yard—a thoughtful technique that scientists call “tolerance.” However, that doesn’t mean I won’t give them a nice, warm look when I walk by (not too close).
One final note: If you don’t notice nests until early summer, there’s no reason to remove them to control pests.
At this point, the caterpillar is fully grown and will soon move on. However, if you don’t like the look of the nets, feel free to sweep them away.
The best option for dealing with these pests is to simply physically remove them. There are several possibilities for this.
Cut off the most affected branches unless the nest is on a larger branch or part of the trunk.
You can also use a broom to sweep the nest onto a tarp, then pack and dispose of the bugs.
Sweep and prune at dusk, early morning, or during heavy rains to ensure you’re removing caterpillars that are resting or seeking shelter, not just the nest itself.
Under no circumstances should you attempt to burn the nest. They will burn, and as they fall off the tree, they will turn into flags of fire that fly on the branches. Not only does this create a serious fire hazard, but it can also damage trees.
Scrape off any egg pieces with a knife in the winter and trim or remove them.
To remove abandoned nests, use a strong stream of water from a broom or hose.
These caterpillars have a lot of natural enemies. Put them to work for you to help keep an infestation under control.
Beyond encouraging birds to visit your garden, you can also introduce ladybugs, tachinid flies, and parasitic wasps in the Hyposter, Cotesia, and Bracon genera, as well as Edovum puttleri.
For example, Arbico Organics stocks adult lacewings and eggs.
Bacillus thuringiensis kurstaki (Btk) is effective against smaller caterpillars less than an inch in length, but less so when they get larger.
Also, by the time the larvae reach adult size, most of the damage to the tree has already been done, so killing them doesn’t do much good.
To prevent caterpillar infestations, spray the egg masses with dormant oil in winter. This will suffocate the egg.
Since application times and recommended amounts vary from plant to plant, follow the manufacturer’s instructions closely.
Spinosyn is an effective control agent with the added benefit of being harmless to most beneficial insects. It also works for a few days after application.
Monterey Garden Insecticide
Monterey Insect Spray contains spinosad, which you can buy in pint, quart, or gallon sized containers.
Finally, insecticidal soap can be a good organic insecticide, but you need to reuse it because the soap needs to come in contact with the larvae to kill them.
Be sure to follow the manufacturer’s instructions for the specific tree species you’re spraying.
Bonide insecticidal soap
Bonide is a great ready-to-use option in 12 and 32 ounce containers.
Chemical Pesticide Control
Since this is not a pest that usually causes devastating damage and there are no insecticides specifically designed for caterpillars, we do not recommend chemical insecticides.
Otherwise, other beneficial insects in your garden could be harmed, with far-reaching environmental consequences.
You should also be extra careful when killing native insect populations, as doing so may have unintended overall negative effects.
There Are Worse Pests to Have
I know my distaste for caterpillars is unreasonable. Your good points really outweigh the bad! They don’t usually kill your plants, they make the birds and other plants in your garden happy and have a positive effect on the garden.
Plus, they’re not too hard to remove if you can’t stand them. As far as pests go, you can do worse. If you can practice tolerance, do it. If not, Answer The Question hopes this guide has given you the information you need to deal with the situation.
If so, please let us know in the comments. Dear tent caterpillar nest aphobes, please contact me so I am not so alone anymore!