Tent CaterpillarsWhen I posted this photo on my Flickr site, I got two comments:

Blech! – makeupanid


Yuck!  I hate these things! – craftermom

The nests are created by Eastern Tent Caterpillars (Malacosoma americanum).  The eggs overwintered and hatched in spring.  The larva are social and live in this shelter they build together, emerging to eat tree leaves when the weather is fine.  Most often, the tents are built in the crotches of trees, but I have also seen them suspended from smaller branches, as pictured below:

Eastern Tent Caterpillars

Eastern Tent CaterpillarOnce the caterpillars have reached their last instar, they will leave the tent to find a place to pupate.  Adult moths will emerge later in summer.  The adults will mate, lay eggs, and die.

Because they can defoliate trees in years when their populations are high, they are considered a pest.  If you “google” them, you will find several sites that not only tell about their life cycle and natural history, but they will also give tips about controlling them.

Learn more:  The following websites have some neat pictures of the eggs, and adults.

Apparently, the populations fluctuate – there are lots one year, and fewer the next.  I’ve been seeing quite a few around this spring.  How about you?  Are you seeing lots around your place this spring?

UPDATE (5-9-2008):  Read this blog post from The Marvelous in Nature for some really, really good pictures and information on these guys!!!!  tenting-it-with-the-family

10 thoughts on “Ewww…

  1. I’ve not seen any here yet.
    I can usually guarantee they’ll find our cherries out back, though.
    There’s no greater satisfaction than throwing the sticky, tangled mass into the pod–fish love ’em!

  2. I did a post last week about them, in fact, because they struck me as being unusually numerous this year. I think they’re unfairly demonized, like many things. Sure, they can eat a bit of your tree, but they rarely kill their host unless it’s sick to begin with, and the trees bounce back later in the season or the following year. They’re mostly just a “pest” because they make the tree look unsightly for a brief period. One of those weird cultural values that’s developed, like having a perfectly green, unblemished lawn. Personally I’d rather have the cheerful yellow of the dandelions than the sterile flat green. And I’d rather sacrifice a few leaves and have the caterpillars to watch.

  3. OOh.. Fish food… Intriguing thought…

    And I agree with you, themarvelousinnature, about lawns and societal norms in general!!!

  4. Great photos of a nifty caterpillar! Love the 2nd photo. I haven’t seen any, and in fact I’m not sure they occur here.

    I’m definitely with themarvelousinnature and you – most “pests” aren’t.

  5. Tent caterpillars are highly variable down here at Roundtop. As you said, sometimes there’s a lot, sometimes there aren’t many. This year, i haven’t seen many so far.

    Carolyn H.

  6. I hate having them in our own trees, and I’ve always been surprised by how out-of-control they can get. I guess that there aren’t many natural predators. I did, however, watch a warbling vireo poke holes in a tent and start grabbing the tasty morsels from inside, so I guess that some birds like ’em!

  7. Bluebirds like them too!
    Here’s my sad story…… Probably about 12 years ago, (and much stupider than I am today) I had a bunch of these caterpillars on one of my crabapple trees. So I sprayed the whole bunch of them with Raid and by the next day they were all dead. Here’s the really sad part–within 2 days my mother bluebird was also dead in her house sitting on 4 eggs and I was responsible for her death by spraying those caterpillars. It took me a long time to figure out that I actually caused her death and the day I did was the day my yard became chemical free. It was a stupid and needless “accident” that will haunt me for the rest of my life. I learned a valuable lesson the really hard way.

  8. No tent caterpillars in the Ozarks yet. Strange that they emerge in the NE before points considerably farther south. I seem to remember our peak infestation occurring in mid to late summer. Admittedly, I’ve never paid that much attention to our tent cats. We could very well have a different species.

    As for how I deal with them: I don’t. Yes, populations vary from year to year, but never reach a level that I’d consider them a problem requiring my intervention. Perhaps natural forces keep the situation under control on our chemical-free homestead. Or, perhaps we are just lucky. I dunno.

    Living out in the boonies, there is no social pressure to eradicate our tent cats so we just leave them be. I don’t know if this is a sign of our sensitivity to the natural world or just plain old laziness. 🙂

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