Pender Gardener: Fall webworms making a mess


Check webs for worms before deciding to treat.

Charlotte Glen / Topsail Advertiser
Published: Friday, September 6, 2013 at 02:10 PM.

Masses of webbing on the ends of tree branches in your yard and along the roadsides are the work of the fall webworm, a species of caterpillar native to our region. Fall webworm outbreaks occur every year in our area and are most noticeable in late summer and fall. This year they are particularly prolific, but fortunately they cause little lasting damage to trees and shrubs.

Where do they come from?

Fall webworms are native to much of North America and are one of the few insect pests introduced from our continent to other parts of the world. The caterpillars currently feeding on trees in our area hatched from eggs laid by adult fall webworm moths earlier this summer. These caterpillars will feed for four to six weeks, then leave the host tree to spin a cocoon in which they will spend the winter. Next spring adult moths will emerge from these cocoons and mate, after which the females will lay eggs, beginning the cycle all over again.

What will they eat?

Fall webworms are not picky eaters and have one of the widest host ranges of any insect. They are capable of feeding on just about any deciduous tree species. In our region, sweet gum, persimmon, and pecan are favorites. This year fall webworms have been noticed in higher numbers and on a wider range of trees than usual, including dogwood, wax myrtle, redbud, and bald cypress.

The mass of webbing spun by fall webworms is known as a nest. Each nest can contain hundreds of webworms, which hatched from an egg mass laid by a female fall webworm moth. The caterpillars in a nest feed together for several weeks, expanding the web as needed. Nests can reach three feet across or more. Fall webworms feed within their nest until they reach full size, at which time they crawl out of the nest, and usually away from the tree, to form a cocoon. You may find individual webworms on your deck, porch, driveway or plants. They are not seeking more food; just a place to spend the winter.

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