Have you noticed large webs in your trees? This webbing is caused by the larvae of the fall webworm. They spin the webs over the leaves as they feed on them. Plum, cherry, chokecherry and apple are their primary targets but the webworm will attack almost any shade or ornamental tree except for the evergreens.

The adult webworm is a silky white moth with black spots. The female lays large numbers of eggs on the underside of the tree leaves. The larvae is a pale yellow caterpillar with black spots on the back covered with fine white hair. As the larvae grow, they extend their webbing over the terminal area of branches. If not controlled, they will feed for 4-6 weeks. After reaching maturity, the larvae will crawl down the tree and construct cocoons, in which they pupate. They over winter in the pupal stage.

Fall webworm damage often looks much worse then it actually is. If the affected trees are small, you can trim out the infested terminals branch areas and dispose of them. Spraying with Malathion, Diazinon or Sevin will give good control. You may tear the webbing apart before spraying for better penetration by the insecticide. Other insecticides labeled for leaf feeding caterpillars such as Tempo can also be used. The active ingredient in Tempo is available in Bayer Advanced Garden Multi-Insect Killer.  When using insecticide, mix and apply according to label directions. If larger trees are infected and control measures are not possible, some leaves will be eaten off, but at this point in the growing season, this loss of leaves will not be critical to the tree's health.

This page was last updated April 2003

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