Help! Our trees have been invaded by tent caterpillars!

April 24, 2007 9:03 AM

Eastern tent caterpillar invasion! How can we safely defend the homeland?

We have two trees in our back yard that are hosting probably gazillions of tent caterpillars. The tents are very high in the trees. They are gross. Soon, I think our yard and our neighbors' yards will be overrun by caterpillars. Any ideas about how to deal with these critters? I'm not inclined to spray because of neighborhood kids and pets. But I'm getting desperate.

posted by WyoWhy to home & garden (13 comments total)

Get a long stick and rip the webs apart. The wasps and birds will then take over. If there's no fire hazard, you can tape a propane torch on the end of a pole and burn them.
posted by weapons-grade pandemonium at 9:25 AM on April 24, 2007

Heh. We used to do the propane torch thing ... we'd *literally* burn them with fire.
posted by SpecialK at 9:29 AM on April 24, 2007

We (my dad) would cut off the effected portions and burn them in a big heap. I've heard that's the only real way to get rid of them and keep them from infesting your trees.
posted by philomathoholic at 9:56 AM on April 24, 2007

We used to have issues with them up in CT ... tearing open the "tents" with a stick is a little gross (don't stand under them while you do it) but effective if you have wasps and birds in the vicinity. (I wonder if maybe tossing some bird seed around to attract some birds and lead them to the nests would be effective?)

I'd think about spot-spraying with some sort of insecticide, just on the nests (rather than everywhere in the garden). I think there are even some organic pesticides you can get, although really I don't know if there's any hard data saying they're less hazardous than the regular kind. I really can't imagine that if you just spray the nests that it's going to be that big an issue for your children or pets.

This page says that some kinds of soaps or plant-derived oils will kill caterpillars on contact, and I have a vague recollection of my mother (always looking to save a few bucks) once making up some sort of dish-soap concoction to spray on our mugo pines when I was a kid, to kill caterpillars.

If you have one of those devices that goes on your garden hose and mixes things into it, maybe you can get one of those organic "insect soaps" and spray it into the nests (after tearing them open with a stick or hook). That ought to do the trick.

One final note; according to this guy, "When you happen to see a caterpillar with white eggs or a cocoon attached to it’s back, don’t kill it; they are hosts of native parasites."
posted by Kadin2048 at 9:57 AM on April 24, 2007

Also, talk to your county wildlife dept, or your cooperative extension service (in phone book, or google "town/county name"+"cooperative extension") - they may have suggestions more tailored to your area.
posted by LobsterMitten at 10:06 AM on April 24, 2007

Thanks so much, everyone.

The tents are way high in the trees. The highest are about 50 feet high. The lowest could be stick slapped (carefully). We can't get up high enough with a ladder and a stick to get the really big ones.

From what I've read, the nests cannot be penetrated by liquid pesticides. There is a product, a hard-assed organophosphate pesticide, that can be injected (1-2 mL per tree) into the tree's roots that may do the job. This has to be done by somebody licensed to use these chemicals---like a certified arborist or something.

The real problem is how high the darned things are. We can't reach them. Maybe we should try rockets?
posted by WyoWhy at 10:08 AM on April 24, 2007

Silly suggestion from the plane-in-a-tree thread...how about balloons with hooks attached? I'm guessing velcro would stick like anything to tent caterpillar nests (just make sure it sticks as well to your balloon). And use a strong string of course, balloon littering is bad.
posted by anaelith at 10:34 AM on April 24, 2007

Am I crazy to think the balloon velcro thing could work? Is this insanity or pure genius?
posted by WyoWhy at 10:41 AM on April 24, 2007

Here's the Wisconsin DNR's advice.
posted by drezdn at 10:43 AM on April 24, 2007

Scroll to the bottom for more tips.
posted by drezdn at 10:46 AM on April 24, 2007

Maybe a well-aimed pressure washer would do the trick? It would probably damage the leaves around the nest, but they're going to get eaten anyway.
posted by Ostara at 11:21 AM on April 24, 2007

I suggest you check with the Master Gardeners at the University of Maryland.
posted by terrapin at 11:44 AM on April 24, 2007

Bacillus thuringiensis (aka Dipel, Thuricide, BT) is an organic insecticide that kills caterpillars, yet is harmless to humans, birds, bees and most other insects. I don't use it any more, because I've been organic so long the birds and insects pretty much control things. The problem here is height, and webbing that prevents the spray from penetrating. They do have to move to new foliage, however, and if you are persistent, they will eventually ingest the BT and die.
posted by weapons-grade pandemonium at 1:19 PM on April 24, 2007