Fall webworm not cause for concern for tree health

Fall webworm not cause for concern for tree health

The fall webworm is a common site this time of year on Northeast Ohio tree branches. Tree experts acknowledge the white tents or webs that appear each year in late July through September on trees throughout the area are not attractive, but beyond the leaves on the affected branch, your tree’s health is not in danger.

Part of the Erebidae family of moths, the fall webworm builds its messy, webby nest at the end of tree branches in late summer during its larval stage. These hairy pale green or yellow caterpillars are rarely noticed until the white tents appear. The larvae feed on the leaves inside the nests for about 6 weeks, when they reach the next stage of life. At this point they leave the nest and the web begins to turn brown, eventually falling out of the tree. Because they feed only on the leaves within the nest, fall webworms are not harmful to an otherwise healthy tree.

Fall webworms are sometimes confused with eastern tent caterpillars, which create similar web nests in the spring. Unlike the fall webworm, eastern tent caterpillars build tight nests in the forks of branches where they congregate at night or during bad weather. Their food source is the leaves outside of the nest and, like fall webworms, they are typically not a threat to an otherwise healthy tree.

What you can do

Tree experts typically do not recommend treating for or attempting to control fall webworms, as they do not harm the tree and they are food for several species of birds and other insects that can be beneficial.

In the case of a young tree that could be damaged by defoliation or if you need to protect regrowth on a tree that was defoliated earlier in the season by other caterpillars or worms, you may consider the following:

• Use a pole or rake to remove the nest or to tear a hole in it to allow natural predators to get at the larvae.
• Prune the branches containing the nests and dispose of them.
• Consult an expert about appropriate insecticides that can be applied directly to the nests.
• Prevent nests from forming by consulting your tree expert about spring treatment for trees that could be harmed by fall webworms.

Fall webworms favor a wide variety of hardwood trees, including hickory, walnut, birch, and cherry. If you have questions or concerns about fall webworms or any other insect that could affect your trees in the Mogadore, Kent or Akron area, contact the experts at GP Tree Service.