Fall webworm feeds on almost all fruit, shade, and ornamental trees except conifers. This insect is present more often on trees that are not surrounded by other trees. The larvae begin by constructing small webs near the ends of branches. The insect will gradually increase the size of the web as the need for food increases.
Mature caterpillars are yellowish with black and brown markings, and have many tufts of long hair. As larvae mature, they crawl down the tree and spend the winter as pupa in the leaf litter under the tree.
High populations of fall webworm can completely defoliate host plants but do not kill them. However, on pecan trees, nut production and quality can be reduced if webworms are not controlled. On ornamental plants, control is optional.
Pruning and destroying the infested portions of branches is a common control practice while webs are still small. A stick or pole with a nail inserted crosswise can be used to snag individual webs. Twisting the pole after insertion will cause the web to wrap around the pole where it can be removed and destroyed. Instead of a nail inserted crosswise, some people use a toilet brush attached to the end of a pole. Insecticides can also be used for control but a commercial quality, high-pressure sprayer is needed to penetrate the webs. Numerous products can be used for control including spinosad (Conserve; Fertilome Borer, Bagworm, Leafminer and Tent Caterpillar Spray; Captain Jack’s Dead Bug Brew), cyfluthrin (Tempo, Bayer Vegetable & Garden Insect Spray) and permethrin (numerous trade names). We normally consider fall webworm damage to be purely aesthetic, and control is not needed to protect the health of the tree.
By: Cassie Homan