The Trees Are Full of Worms

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We are fortunate to have plenty of large, beautiful trees here in Burke County. The rich, green of their leaves gives a fresh and vibrant look to our area. But not so much lately…these days our trees are full of worm nests – fall webworms to be exact. This office is getting many calls about the abundance of large, webby-looking nest in area trees. “What are they and how can we get rid of them?” are the questions everyone is asking.

Contrary to popular belief, they are not tent caterpillars. Tent caterpillars build their nests in the spring and are found in the crotch of trees while fall webworms build their nests in late summer and are usually located at the ends of the tree limbs, surrounding clusters of leaves. These caterpillars feed on more than 90 different deciduous trees including hickory, crabapple and cherry.

Adults overwinter in a cocoon hidden in cracks and crevices or in the soil and begin to emerge in mid-June. The adult moths lay egg masses on the undersides of leave and they hatch in about 7 days. The young caterpillars immediately start to build a silken thread nest around foliage on which they feed. As they grow, the nest is enlarged to take in more foliage for food. After feeding for about 6 weeks the mature larvae return to the soil where they pupate over the winter.

It all sounds and looks worse than it really is. Because the feeding of the larvae happenings in late summer, no real damage is done to trees even when they are defoliated. Sufficient food has already been stored to get the tree through the winter so the absence of leaves does no harm to the tree. Of course, it makes the trees look terrible and the caterpillars are pretty ugly so folks don’t like them, but in the long run they are harmless and no trees are permanently damaged during the process.

If nests are low enough in the tree, they may be pruned out and destroyed but take care not to ruin the shape of the tree when pruning. Nest can be sprayed with pesticides such as liquid Sevin, malathion or spinosad when they are small but after the webbing becomes thick, pesticides cannot penetrate the protective covering. Whenever pesticides are used, be sure and follow the directions for use located on the pesticide label.

On a cheerier note, did you ever think about the fact that if the leaves are eaten by fall webworms, you won’t have to rake them this fall? Just something to think about!

Written By

Photo of Donna TeasleyDonna TeasleyExtension Agent, Agriculture - Horticulture (828) 439-4460 Donna_Teasley@ncsu.eduBurke County, North Carolina
Posted on Aug 26, 2016
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