Creating a wildlife haven one plant at a time

Friday, March 25, 2011

Eastern Tent Caterpillar

Have you ever seen this moth in your garden?

Photo courtesy of the UGA Cooperative Extension Service

This is the moth of the Eastern Tent Caterpillar (Malacosoma americanum), a native insect to the Eastern United States. Like all moths they undergo a complete metamorphosis (egg-larva-pupa-adult). The eastern tent caterpillar overwinters within an egg mass of 150-400 eggs. These masses are covered with a shiny, black material that encircles the branches of a tree. The masses are about the same diameter of a pencil. In early March, the eggs hatch.

It is one of the few insects that is recognized by most people by its home rather than appearance. The caterpillars are social creatures living together in large silk nests that they build in the crotches of trees. They are often seen on trees along the road in sunny locations. These caterpillars need the sun to heat their bodies so their nests are rarely found in shaded woodland areas.There are usually hundreds of caterpillars in a nest and it isn't uncommon for caterpillars from two or more egg masses to join together to form one colony.


This is one I found in my garden. The caterpillars leave the nest several times a day: usually before dawn, midday and after sunset when it is not too cold. They feed on the leaves of ornamental landscape trees such as wild cherry, apple, crabapple, hawthorn, maple, peach, pear and plum. Note that in the adult stage (moth) they only live a few days and do not eat. I took these pictures early in the morning before they left the nest.


If you don't find it unnerving to look at hundred of caterpillars en masse, they are really interesting to watch. Here are two leaving the nest in search of breakfast. You can see the silk from the nest and how it covers the trunk of the tree.


This photo was taken later in the morning after most of the caterpillars had left the nest.



They are considered a pest because of their unsightly nests, the damage they do to trees and masses of wandering caterpillars on plants, walkways and roads. They can defoliate trees rather quickly if there is a large population but rarely do they do enough damage to kill a healthy tree. The trees usually recover and put out a new crop of leaves once the caterpillars are gone.

Do you have these caterpillars in your garden? How do you manage them?
  • let mother nature do her thing and leave it to the birds and parasitic wasps to keep the caterpillar populations under control.
  • take preventative measures and remove the egg masses during the winter.
  • remove the nests and kill them using natural methods such as drowning them in soapy water, suffocation in an air tight container, or burning them.
  • spray an insecticide to kill them.

23 comments:

  1. Those caterpillars are fascinating in a car accident can't look away kind of way. I've never seen anything like it and if I do I'm likely to turn a blind eye. I want nothing to do with that wriggling mass!

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  2. I used to have these all over growing up in GA, and we have some (though not as many) in NC. Im sure the best removal method would be to get the egg masses in winter, but as a kid my pyro-brother liked to burn them... I never wanted anything to do with that. Now my husband freezes them and uses them as bait for fishing! A little more humane way to deal.

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  3. Marguerite, your comment made me laugh out loud!

    Lisa, what a fabulous idea! My husband and boys love fishing! It never crossed my mind to use them as bait. Thank you!

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  4. Hello Karin,
    Goodness, that nest would stop you in your tracks wouldn't it?! I have to admit, I do like the texture of the moth that they develop into, he looks like one furry little critter!
    I've only just started to have a look around your blog, but am falling in love with all the bugs and butterflies :) Heidi

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  5. These are a real pest,but I have not had them in my home garden's trees. I have seen them at the farm and as long as they are not on the nursery trees, no spray will touch them.

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  6. These caterpillars, which as you said cause no permanent damage to the trees they inhabit, are an extremely important food source for birds and other animals. I am glad you gave a range of choices because if we are to survive environmentally we have to look at them as beneficial and leave them alone. Where did we get this idea that everything has to look perfect? Thanks for highlighting this insect.

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  7. I thought I have a lot of caterpillars in my garden until I saw your tree. I used to remove the caterpillars but not anymore. I have seen spiders attacking them and eating them up. I'm sure the birds will be happy to find them too. I notice birds tend to look around the branches and leaves of a tree as if looking for something yummy.

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  8. Wow, using them as bait seems like a great idea! I have to be honest that even though I know they're not terribly harmful, it's hard for me to look at them. We have them up at our cottage and they creep me out. We usually just let them go. But gypsy moths, which look a lot like them, can do a lot more damage.

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  9. I have these in my garden, and they are so frustrating! I thought they would hurt the trees, though. I have not done anything to them (they are too high), but I have been worried about them multiplying and hurting my favorite garden trees. I hope the birds hurry up and find them!

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  10. Gippslandgardner, thanks for visiting and your sweet comment!

    GWGT, they are unsightly and I am hoping they don't touch my "good" trees.

    Carolyn, absolutely right...nature will take its course and often it is not the prettiest sight but it is the cycle of life. I am finding I have more robins in my garden.

    One, yes, I will leave them for the birds. Some nests are too high to reach anyway. I am imagining how many moths there will be if the birds don't eat them.

    PlantPostings, yes, they are kind of creepy when you look at them close up. But they are fun to watch since they move around so much. Bait is a great idea but I won't be the one getting them out of the nest for that!

    HolleyGarden, I have the same worries but I will wait and see what happens. They are frequently parasitized by wasps which helps keep populations under control but sometime when natural enemies are not as productive there are population explosions.

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  11. Oh I do hope I never see this in my garden. I don't know what I would do after I screamed in horror :)

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  12. I had them quite a bit up north Karin. Here in the south I am over run by all kinds of "worms" in my woods that chew the leaves off the trees and their little poop actually rains down on my head!!!
    What I did with the tent caterpillars up north was take a stick, and when they were very young in their tents, swirl them up in the stick, put them on the ground and do a little "take that" kind of dance on them! Believe me there were plenty more out in the back forty to keep the birds happy!
    Down here in the south I'm still scratching my head on how to get rid of all the bad guys in the woods. I'm goping they come in cycles and this year they will move on to some other part of the county!

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  13. great post with important info to give people options...hopefully they will leave them alone so the critters feeding on them can...

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  14. Eewww...my hairs stand on their ends looking at those bunch of creepy caterpillars! I just cant imagine if they do invade my garden...all my plants will be kaput in a day!

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  15. Karin: I hope it's OK that I linked to this post from my post about turkey vultures: http://plantpostings.blogspot.com/2011/03/creepy-creatures-in-oak-canopy.html. --Beth

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  16. Hi,

    I wanted to email you in regards in any possible advertising opportunities you may have with your website. I'm looking to earn support for a national cause and get visibility for the "plant 1 billion trees" project. Let me know if you would be interested at all in supporting this cause or if you want more information on it. I look forward to talking to you soon!

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  17. I'm with Marguerite on this. Don't really like the looks of them but still staring at that nest of yours anyway. Sorry I can't help with the advice. The ones I have are few and far between so I usually just let them be.
    -- Bom

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  18. I had a nest of these in a plum tree once. I removed the nest and threw it in the brush pile, then hosed the tree down with a strong spray of water.

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  19. I blast them with the hose and then squish any survivors. PLEASE don't use a pesticide!!!! Several blastings and squishing will do the trick. I like the burning ideas, too.

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  20. GardeningBlog, I think mother nature has provided you with enough creepy creatures that she will spare you these wiggly creatures!

    Eve, I am finding several nests that are too high up to even reach and I feeling squishy bugs under my feet creeps me out!

    Thanks Donna! I hope that people will consider all the alternatives before using pesticides. We both know the consequences of that are worse than the harm the critters are doing.

    p3chandan, it takes many more caterpillars to defoliate an entire garden. I am noticing more and more nests in the area. Hopefully we don't have a population explosion this year.

    PlantPostings, thank you for the link! Great posts on Turkey Vultures!

    Nerrisa, thanks for stopping by. I appreciate your efforts but I don't do advertising on my blog.

    PlantChaser, strangely the caterpillars are a little captivating. I have been watching this nest daily for a week now.

    debsgarden, thanks for the tip on hosing down the tree. That will knock off any stragglers not in the nest.

    Casa Mariposa, No worries! I don't use pesticides in my garden! I only listed it since it is an option that some people may have used. Right now, I am leaving them for the birds. I like the idea of using them as fishing bait but I won't be the one taking them out of the tree.

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  21. We have tent caterpillars here in Missouri, but I have never seen them that HUGE! It's funny how gardeners think alike.. If that nest was in one of my trees, I would be taking daily photos of it also! (Fishing bait does sound like a good idea!)

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