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Yale Park Homeowners Association

Texas AgriLife Extension Service

Kimberly Schofield
Program Specialist-Urban IPM

Fall Webworms

The fall webworm, Hyphantria cunea (Drury), is usually noticed when the light gray, silken webs are discovered on trees in late summer and early fall.  Webworms enclose leaves and small branches within their webs.  They are considered pests of shade and ornamental trees in urban areas, attacking more than 88 plants.  Four generations occur in the south Texas, with 2 to 3 generations occurring in northern Texas.  The last generation in the fall is usually the most damaging.

The caterpillars build webs soon after hatching and they will remain inside the webbing to consume the tender parts of the leaves.  If the caterpillars consume all of the leaves within the web, then new foliage is encased within the webbing. Caterpillars are 1 inch in length and they are pale yellow or green in color, covered with white and black tufts of long hair.  The caterpillars will molt 6 or 7 times before dropping to the ground to pupate.  Pupae are usually in the ground but can be located under loose bark and in leaf litter.  The pupae overwinters and the adult moths emerge in the spring.

Some Control Options:

Mechanical Control:  Small webs can be removed by pruning and destroying the infested portions of branches.  Also, a stick or pole can be used to snag individual webs.  By twisting the pole, the web will wrap around the pole so it can be removed and destroyed.

Biological Control:
Social wasps such as yellow jackets and paper nest wasps, birds, predatory stink bugs and parasitic flies are some of the natural enemies of fall webworms.  Bacillus thuringiensis, B.t,. is effective against fall webworms if it is applied when the caterpillars are small. It is better to apply after the eggs hatch and the web is not so dense. Also spray surrounding leaves, since the B.t. coated leaves will also be eaten by the caterpillars.

Chemical Control:
Chemicals should be applied after eggs hatch, since they are most effective on young caterpillars. Insecticides such as those containing spinosad and tebufenozide as active ingredients can be used. Multiple applications may need to be applied as generations occur.

Fall webworm, Hyphantria cunea (Drury)
(Lepidoptera: Arctiidae), web on pecan.
Photo by Bart Drees, Texas A&M University.

Mention of commercial products is for educational purposes only and does not represent endorsement by Texas AgriLife Extension or The Texas A&M University System.  Insecticide label registrations are subject to change, and changes may have occurred since this publication was printed.  The pesticide user is always responsible for applying products in accordance with label directions.  Always read and carefully follow the instructions on the container label.

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