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I have a small bush/tree. I don't know exactly what it is. What I see is the new growths folded over onto each other, and connected together. When I pull them apart, I can find tiny white worms with black heads, which are about 5/8 inch long.

The worms have eaten the new growth, severely stunting it.

I tried treating with insecticidal soap to no avail, probably because it can't get to the worms as they are all safe in their tent. I also tried "BT" hoping they were some sort of caterpillar. It appears that has not worked either as I see no affect. The next step I guess is to pull out the tree.

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Definitely post pictures. Try to get a close-up of the worms, a shot of the "tent", and a shot of the tree so that it can maybe be identified. –  bstpierre Apr 29 '12 at 20:32
What kind of tree is it? They look like the tenting-caterpillars we had a mass outbreak of a few years back here in the DFW area. Those preferred mulberries. After seeing some amusing amateur fumigation going on at the time (probably killed more human brain cells than caterpillars), I wonder consider professionals to deal with anything more than 6ft high. –  winwaed Apr 30 '12 at 12:54
As well as moth caterpillars, don't forget butterflies. On a nature walk on Friday MrsWinwaed reported seeing lots of butterflies curling ash leaves and laying eggs (also some caterpillars emerging). She had a lot of kids with her who thought it was the coolest thing. In other words, even though they might make a mess of the leaves, they might be something you want to keep. –  winwaed Apr 30 '12 at 12:56
I followed your link to the pictures - there aren't any, its an empty folder. –  Bamboo Jun 29 at 12:16
Pulling out the tree is over-reacting. I grew up "cutting the webbed branches off and destroying them (generally by fire)" - later on in life an entemologist I met claimed that ripping the webs open so that birds could get at them was just as effective. –  Ecnerwal Jul 15 at 3:44

1 Answer 1

It sounds like you have Eastern Tent Caterpillars, Malacosoma americanum. This is a very common pest in the U.S.. You can cut off affected branches, and destroy them. Make sure the caterpillars are killed. You can also use a broad-spectrum insecticide early in the season. This may not penetrate the web, so it isn't the most effective method of treatment.

There are certain parasitic wasps that will attack these worms, also. You may want to research that as an alternative control method.

I recommend using more than one control method, for better results. I have also found that Eastern Tent Caterpillars rarely become a serious issue on the same plant several years in a row. They'll generally be very bad one year, and only moderate or mild the next.

The shrub/tree you are having trouble with is probably in the rose family, because those are the main host plants for these pests, although they will attack other plants.

Here are more resources on Eastern Tent Caterpillars:

1) https://insects.tamu.edu/extension/publications/epubs/e-218.cfm

2) http://insects.about.com/od/insectpests/f/tentcaterpillar.htm

3) http://bugspray.com/catalog/products/page1896.html

4) http://www.planetnatural.com/pest-problem-solver/tree-pests/tent-caterpillar-control/

5) http://ohioline.osu.edu/hyg-fact/2000/2022.html

6) http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/insects/caterpillars/eastern-tent-caterpillar.aspx

7) http://www.organicgardening.com/learn-and-grow/tent-caterpillars

8) http://watoxics.org/files/tentcaterpillars.pdf

9) http://www.gardeningknowhow.com/plant-problems/pests/tent-worms-tent-caterpillar-home-remedy.htm

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