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Fall Webworm

January 2, 1998

Fall webworms continue to be very numerous throughout Illinois. The silk tents at branch ends of crabapple, walnut, hickory, maple, and many other trees usually contain 50 to 100 or more hairy, yellowish caterpillars. There are two races of fall webworm--one has a red head and several light-red spots on the back along with many tiny black dots; the other race has a black head and many large spots scattered along the back, giving the appearance of a black stripe from a distance.

Most colonies are very sizeable and contain large caterpillars, which makes insecticidal control of little value. Hand removal of the tents containing the caterpillars by pruning (or simply pulling) the tent off of the branch, is probably the best methods of control at this time, and removes the aesthetic injury to the tree. Attacked branches are usually alive and will produce leaves next spring if left on the tree.

Author: Phil Nixon


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