YIKES! That looks like a horror movie!! There is something organic that you can spray on the underside of the leaves, and the topside of course, called BT.

What is Bacillus thuringiensis (Bt)?

Bacillus thuringiensis, usually referred to as "Bt" (pronounced "bee-tee"), is a naturally occurring bacterium that is lethal to most leaf-eating caterpillars on trees, shrubs, flowers, and vegetables.

Bacillus thuringiensis variety kurstaki (B.t.k.) is the general purpose material that homeowners buy when they see just the words Bt or Bacillus thuringiensis without the variety name attached. This is the type of Bt that is appropriate for home landscape use to kill caterpillars. As you can see on the left, there are also varieties designed to kill mosquitoes or potato beetles.

Bt is harmless to all other insects, animals, and humans. It comes in powder form for use as a dust or, diluted with water, for use as a foliar spray. It is also available in liquid form. It is sprayed or dusted on leaves of plants that are under attack by caterpillars so that the pests will ingest the bacteria as they eat the leaves. The Bt causes paralysis of the caterpillar's digestive tract, causing it to stop feeding within two hours. Within a day or two, certainly no longer than 72 hours, the caterpillars die.

Good luck to you!

Suzi

It looks like the Eastern Tent Caterpillar which is on the Endangered Species List and carries a $ 10,000.00 fine for each caterpillar you destroy or harass.

How many of those caterpillars did you pick off by hand and crush?

JK lol.

Bart:

I agree with JK lol that you have the Eastern Tent Caterpillar. But I don't see the tents, so you must have removed them before the photo was taken.

My reaction would be a hand trigger sprayer and an application of Malathion. In fact, when you see the tents earlier in the season, even Sevin (carbaryl) will finish them off while they are still very small. You have to keep an eye out for the tents in the month of June, since they seem to show up overnight.

Eggs of the tent caterpillar are laid in a band around small branches, and look like a ring of brown styrofoam. If you do a really thorough spray with oil in the dormant season, it will smother the eggs and they will not hatch. Dormant oil is my principal control for this pest, but when I miss a few egg cases I hit the tents with an insecticide immediately after discovery.

Don Yellman, Great Falls, VA

Thanks everyone.

I never saw any tents on the tree which seems impossible but it's true. I don't know how I could have missed them.

Is it possible that this is a different type of caterpiller? From doing a google search, the Eastern Tent Caterpiller looks to have fewer stripes, but thicker stripes than what I saw. Mine have at least 8 thin alternating stripes - yellow and brown, while the ETC photos I've found seem to have one fat stripe down the back.

Are they just young versions of the ETC or something else?

Thanks again,
Bart