The Richmond Register

April 30, 2013

Are Eastern Tent Caterpillars infecting your trees?

By Amanda Sears
Extension Agent

MADISON COUNTY — Look around your yard and you may notice the appearance of webbing in the branch crotch of some of your trees.

Look closer and you will notice this webbing is filled with small caterpillars. This is the Eastern Tent Caterpillar (ETC). This caterpillar defoliates trees (eats leaves), especially on wild cherry, apple and crabapple, although it can also be found on hawthorn, maple, cherry, peach, pear and plum as well. The ETC is often called a bagworm, however the bagworm is another type of caterpillar which does not live in webbing.

The Eastern Tent Caterpillar overwinters as an egg sac on the branches of trees. They begin to hatch at bud break in early March.

The caterpillar is hairy and black with white stripes down their backs and brown and yellow lines along their sides. The adult moth is reddish-brown with two pale stripes running diagonally across each front wing. The ETC are social insects and congregate together in a silken tent they spin in the crotch of the tree. The caterpillars feed mostly in the morning or at night, defoliating the tree that holds their silk nest. As the caterpillars grow, so does the nest.

When a large nest is present, the tree could be defoliated. Most likely, the tree will recover and put out a new crop of leaves. However, the nests and lack of leaves is an eyesore. While the web tent is still small, take it out. The caterpillars will not hurt you if you do this bare handed, however if you feel squeamish about it, put a plastic bag over your hand and rake out the nest. Destroy it. If the nest is large, you may need to prune it out of the tree. Often people will attempt to burn the nest while it is in the tree.  This is not recommended since it will damage the tree.

Insecticides are only effective against the young, small caterpillars.  Use an insecticide with Bacillus thuringiensis var. kurstaki, carbaryl, methoxychlor, or malathion as the active ingredient. Once inside the nest, they are protected from insecticides.

Tree Identification Class

Always wanted to learn how to identify trees? This is a great opportunity for you! Dr. Doug McLaren, UK Forestry Specialist, will teach the principles of using an identification key when looking at trees on Tuesday, May 21, from 6 to 7:30 p.m. He will go step by step through the process and tell you what parts of the tree to focus on when identifying.

After attending this class, you should have the means to identify trees. Agent Scott Darst also will be offering a class at the same time on creating a 4-H leaf collection that can be entered into the county and state fair.

To save a seat and so that we have enough supplies, please call 859-623-4072.