As the end of summer looms, one of the most noticeable insects hits its stride. These insects are not as eye-catching as the home that they build for themselves. The fall webworm, or Hyphantria cunea, will be webbing the ends of branches near you soon, if it has not already. A big, showy bag of webbing appears over the end of a branch on a shade, fruit or ornamental tree. Inside, the hungry fall webworms are devouring all the leaves. It is highly visible and leaves are being consumed.
Fall webworms have a wide variety of trees for potential food. Over 90 species of deciduous trees make the menu with fruit and nut trees, like walnuts and elms, and some maples as regular targets. It is unusual to see fall webworms in the same tree year after year and especially on the same branch. They are “one and done” feeders.
Eggs are laid by the female moth on the bottoms of leaves about a month or so before the larvae or caterpillars hatch. The caterpillars construct a web over the end of the branch, enclosing leaves. They feed inside the web, enlarging it as they feed. Their lives as larvae are usually about six weeks, but long after they have left, the webs remain. If the web is white, it is new. If it is tan or brown, there are no larvae there. Webs can last into the winter before falling out of the tree during a wet snow or a windstorm.
Fall webworm damage generally looks much worse than it is. In general, trees only need to be managed for fall webworm if the owner is concerned about aesthetics. In that case, the easiest means of management is pulling the web off the tree by hand and putting it in a bucket of soapy water or freezing it. Some people may be sensitive to the caterpillars’ hairs so gloves should be worn to prevent contact.
We offer a Trunk Injection (Arbor Jet), this can provide protection for up to 2 years. Please give Tri-Hill a call at 479-782-0404 if you are interested in getting a price for this or any other treatments.