Subject: Fall Webworms  - E Letter

If you’re observing carefully, you may have noticed that fall webworms have begun to show up. Fall webworms create a tent like webbing that serves as a place of respite when they are not busy feeding on the foliage of plants where their mother laid eggs. Unlike the eastern tent caterpillars that were present earlier in the year, fall webworms tend to feed out at the ends of branches.

As the infant caterpillars feed and grow, they also increase the size of their home. The tent may eventually span 2 to 3 feet by the time fall actually arrives. While the damage they do is fairly inconsequential for established trees, many gardeners find the webbing less attractive than flowers. And the feeding may actually do serious damage to young trees. Those who would like to add this species to their insect collections should consider planting trees such as pecan, persimmon, sourwood, or willow. Other species will work but these seem the most dependable.

If you really have it in for these guys and want to do all the damage you can, it’s best to sneak up on them at first light or at dusk. Rainy days work well too. During these times most of the caterpillars are relaxing at home with their mates. This is the time when you can get maximum results from minimum input.

If you can reach, you may be able to simply prune out the nest with all its occupants. If it’s a little out of reach, a carefully selected stick can be inserted into the tent and then used to simply wrap them up. Because the webbing is sticky, a few loops will usually bring them all into a compact wad on which you can wreak your retched vengeance. If a stick won’t reach but a sprayer will, a number of insecticides can be effective. Bacillus thuringiensis (B.t., Dipel) is the least toxic to humans. Once they eat some of that, they lose their appetite completely. Sevin will work even if they don’t eat it and is more effective after they have already done most of their damage. If the sprayer won’t reach them, then you may just have to work on the live and let live philosophy. They don’t eat that much.

Some people have traditionally used fire and torched the poor worms. I think people who like to play with fire may create more hazards than webworms do.

Al Cooke
Extension Agent - Agriculture
Chatham County Center
North Carolina Cooperative Extension Service
N C State University
PO Box 279
Pittsboro, NC 27312
919.542.8202, FAX 919.542.8246
al_cooke@ncsu.edu http://chatham.ces.ncsu.edu/staff/acooke/home.html