2007 Year in Review

Immediate Tent Caterpillar Control Will be Effective

Remember the caterpillars that made silk tents in the twig crotches and ate the leaves of your crabapple tree last spring? These insects, the eastern tent caterpillar, have hatched and may be feeding on your trees, states David Robson, University of Illinois Extension horticulture educator. The eastern tent caterpillar prefers wild cherry, apple, crabapple, although it also feeds on ash, birch willow, maple, oak, poplar, cherry, plum, and several other tree species.

This is one of the first insects to hatch in the spring, closely following bud break on the host tree. The young caterpillars gather at a branch fork or crotch and spin a white silk tent about one inch in diameter. The caterpillars stay inside of this tent at night and during rainy weather.

During the day, the caterpillars crawl out onto the branches, spinning out a single strand of silk as they move away from the tent. Before nightfall, after feeding on the leaves during the day, they retrace their steps along the silk strand back to their nest. As the caterpillars grow, they enlarge their silken tent. They develop a white stripe down the back with a row of blue spots bordered with longitudinal yellow lines on either side of the stripe.

About the end of May, these caterpillars separate and each one spins a white silken cocoon on the tree trunk or some other object in which he pupates. The adult moths emerge in June. After mating, the females lay their eggs on twigs that are usually about the diameter of a pencil. The egg mass is dark brown and usually extends completely around the twig. Each egg mass is about three-fourths of an inch and contains 150-350 eggs. These eggs do not hatch until the following spring.

Control of these insects can be accomplished by several methods. Particularly on small trees, such as crabapple, the silken nets can be removed at night when the caterpillars are inside. The caterpillars can then be squashed or dropped into kerosene or alcohol. The trees can be sprayed with an insecticide to kill the larvae as they feed on the leaves. Heavy infestations can be eliminated for next year by destroying the egg masses between July and April. Contact the local Extension office for the latest recommendations.

by  Editor, theCity1.com
May 21, 2007