Troup County Extension agent: Fall webworms making appearances

Published 12:00 am Friday, August 28, 2015

Brian Maddy

Contributing columnist

As you drive along the highways and byways of Troup County you begin to notice the silken-like bags hanging in trees. You may begin to see the structures forming in early summer but most start to become visible in the latter part of summer.

Fall webworms are making their yearly appearance.

These natives of North America love to munch and crunch on oak, pecan, hickory, fruit and ornamental trees. The only conifer they feed on is the bald cypress. They can also infest mulberry, persimmon, cherry, sourwood and sweetgum trees.

Where they get into trouble is when they attack a small fruit tree or ornamental tree in someone’s yard. Because they feed in large colonies, they have the ability to defoliate a tree. This pale green or yellow caterpillar with a broad dusky stripe that runs down their back, bordered by a yellow stripe and covered with tufts of long whitish hairs, is a handsome fellow.

There are two distinct forms of the fall webworm, the orange-headed and the black-headed. Both forms are common to the Southeastern states and may have up to three to four generations per year. The adult moths may be pure white or white with dark wing spots.

Their wingspan is from 1.4 to 1.7 inches. The adult webworm moths appear mostly from May to August and lay their eggs, if they are orange-headed, on the underside of the leaves in masses of 300 to 1,000, and if black-headed, on both sides of the leaves.

Once they hatch, they begin to spin their silken enclosures as they feed on the leaves. The orange-headed variety makes dense multi-layer webs and the black-headed — lighter, more flimsy webs.

During daylight hours the orange-headed feed indoors and leave the web at night to feed. The adult larvae will then migrate to the ground to pupate.

The black-headed will divide into smaller groups and abandon the web. They feed for four to six weeks and skeletonize the leaves. They can have more than one brood per year.

Most trees can survive the defoliation damage caused by the webworms, but if it continues over a period of years, the tree may experience dieback. If it’s a smaller tree the damage may be more severe.

On smaller fruit trees and ornamentals, you can knock down the nests, but be careful around power lines. Because they are native, there are a lot of predators that consider them lunch, such a birds and parasitic wasps.

You can also spray the nests, if within reach, with an organic pesticide such as Dipel, Bacillus thuringiensis. Carbaryl, which has a trade name of Sevin, and acephate, which has a trade name of Orthene, can also be used. Make sure you read and follow all label directions.

What’s going on in Extension?

Market on Main begins Saturday mornings from 8 to 10 a.m. Come by and enjoy the pick of the day. Carmike Cinemas LaGrange 10 movie theater parking lot at East Depot and Main streets.

Sept. 15: Troup County Cattleman: Forages and Nutrition: Dr. Lawton Stewart, guest speaker; 7 p.m. Tuesday, program will start at 7:30 p.m. The $6 meal will be served at 7 p.m. Ag Center.

Sept. 21: Troup County Association of Beekeepers; 7 p.m. at the Ag Center.

Sept. 24: OSHA Chain Saw Class, 8 a.m. to 4 p.m. Call the office for details.

If you have any questions or concerns, stop by or call the office.

Brian Maddy is the ANR Agent for Troup County Extension. The Troup County Extension office is located at 114 Church St. in LaGrange and may be reached at 706-883-1675, Monday–Friday 8 a.m.–noon and 15 p.m.