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Eeek! Why Are Giant Spider Webs Covering My Trees?

15 de september de 2023

«Oh, gross!» wailed Donna, my sister-in-law, as we drove along the highway in West Virginia last week. «Look at all those giant spider webs in the trees! We have them at our house too!» I could sympathize with her concern. Many people are afraid of spiders, especially giant ones that eat people.

Fortunately, her fears were unfounded. These webs were the work of fall webworms. Fall webworms rarely eat people.

Fall webworms are caterpillars that hatch from eggs laid in the branches of hardwood trees by a nondescript, whitish moth. The caterpillars proceed to enshroud the ends of branches with silky webs, so they can feed on the leaves inside while hidden from predators. They range in color from pale yellow to dark gray, have yellow spots and long, bristly hairs, and grow an inch or so long.

People often confuse fall webworms with Eastern tent caterpillars that also build webs in trees and eat leaves. The two are easy to distinguish, though. Eastern tent caterpillars appear in spring and construct webs in the crotches of branches. Fall webworms show up in late summer and fall and confine their webs to the ends of branches.

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Fall webworms aren’t picky eaters and feed on many different tree species. However, pecan, hickory, mulberry, sycamore, birch, sourwood, fruit trees, and willows seem to be favorites. I’ve seen big pecan tree with 25 or more webs in it and all its leaves devoured. The good news is that fall webworms do no serious damage. This is because the leaves they’re eating would naturally fall off in a few weeks anyway, so it’s no big loss to the tree.

What you should do if you find webs in your trees this fall? Well, if the web is close enough to reach from the ground, you could cut off the branch and throw it away. Or you could tear open the web and let birds and wasps eat the caterpillars. If webs are high up, though, just ignore them. Consider them another miracle of nature.

Do run, however, when confronted by a 100-foot, marauding tarantula. Run very fast and scream!