Question: I have a large piece of property and so many of my trees have large webbing on the branches. Are my trees dying and do I need some type of control?
Answer: Driving around the county you can't help but notice so many of the trees with large areas of webbing covering their branches. A caterpillar, known as the fall webworm is making its home in the webbing.
This native pest found throughout North America is most noticeable in late summer and early fall. It feeds on more than 600 different species of trees and shrubs, but is most commonly found on hickory, walnut, birch, cherry and crabapple.
The fall webworm is commonly mistaken for the eastern tent caterpillar. Both are known for their large conspicuous webs. But the easiest way to distinguish the two is the fall webworm forms its nest at the end of a tree branch, whereas the eastern tent caterpillars webs are formed in the crotch of a branch and the tree. The eastern tent caterpillar also makes its nest in the spring rather than the fall.
The fall webworm starts out living as a pupa in a cocoon in leaf litter, cracks and crevices, and in the soil. The adult moths begin to emerge in mid-June and continue throughout the summer.
The females lay their light, yellow eggs by the hundreds on the underside of leaves. The eggs hatch in seven days and the larvae immediately begin to spin their web covering the foliage that will be their source of food. As they grow, the web enlarges around more foliage. Once mature they leave the nest and drop to the soil where they will spend the winter.
The caterpillar stage of this pest skeletonizes all the leaves inside the nest as they grow. They may grow so large they defoliate large sections of a tree or shrub. This usually does not kill the tree or shrub because the attack is late in the season and the plant has acquired most of the energy it needs before winter. Repeated attacks may stress the plants and make them more susceptible to other pests.
Fall webworms are usually kept in check by natural predators such as birds, other insects and mice. If a tree in your backyard has the webbing it is easily removed by pruning or just taking a stick and poking around the webbing until it is destroyed. Chemical insecticides are seldom necessary. If a larger tree or area in your backyard is infested a professional arborist should be consulted.
Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Exten-sion, 6260 Old Harding Highway, Mays Landing, NJ 08330. Email: