It may not be fall, but the fall webworms are back. There is disagreement whether this is an early generation or a subspecies which arrives first. Either way, fall webworms are beginning to appear on their favorite trees such as sourwood, pecan, and persimmon.

Fall webworm damage increases over the summer. They usually cause little long-term damage to the health of the trees they defoliate unless the trees are completely defoliated year after year. At any one location, the populations of fall webworms increase and decrease in numbers so that they are conspicuous and damaging for a year or two and then the populations seem to disappear.

Through the summer, the webs become filled with cast skins, droppings, and dead leaves. The web is enlarged to enclose fresh, green leaves until the web may become two to three feet long. Small trees infested with several broods of caterpillars may be entirely covered in webs. After feeding for four or five weeks, the caterpillars crawl down, spin cocoons, and pupate in mulch or soil.

In July and August, another generation of moths emerges from the cocoons to continue the life cycle. There are two or three generations each year in North Carolina depending upon how early or late in the spring the first moths emerge. They overwinter as pupae in cocoons in the litter.

White fall webworm moths emerge to mate and lay 350 to 900 eggs on the lower leaf surface. The hairy caterpillars spin the webs as they feed. Fall webworms can be destroyed by pulling down the webs and destroying the caterpillars if the webs are in reach of a pole.

If the webs are within reach of a hose-end sprayer, several insecticides can be sprayed for control. Insecticides work best when the caterpillars are young. Thus it is best to treat as soon as the webs are first noticed. If the trees are too tall for equipment used by the amateur horticulturist, many professional landscapers and arborists offer tree spraying as a part of their services. Bacillus thuringiensis and Orthene are two of several pesticides labeled for fall webworm control.

If you want more information on the control of webworms, call the Cooperative Extension Service at 671-3276 and ask for Insect Note Number 46 entitled Fall Webworm.

E-mail address: Missy_Hoggard@ncsu.edu

Mailing Address:
P. O. Box 2280
Lumberton, NC 28359-2280

Phone: 910-671-3276
Fax: 910-671-6278

Date Created 7/28/98.
Date Revised 11/19/03