Fall Webworms: Do they web your tree?

Fall webworm nest
Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org

As summer comes to an end, unwelcome pests like to visit landscapes; recently, it’s been the Fall Webworm, Hyphantria cunea

Webworms begin showing up in spring but tend to go unnoticed until this time of the year when the second generation appears. Alarm hits homeowners as they watch the bugs creep their way onto leaves and branches, crafting webs as they go. It’s safe to say the moth creates an overwhelming eyesore.

Susceptible Trees: What trees do webworms like?

Rather than threatening tree health, the fall webworm threatens tree aesthetics. Webworms are often seen in large trees but usually do more damage to smaller ornamentals.

These bugs affect about 90 tree species. In our area, they like targeting hickory, walnut, elm, birch, cherry, redbud, willow, oak, mulberry, crabapple and certain maple trees.

Signs and Symptoms: What do fall webworms look like?

Webworm larvae are light yellow with two black marks across their body, while mature caterpillars have white or black wings, black or red heads, and are covered with silky gray hairs.

Defoliation by fall webworm
Bruce W. Kauffman, Tennessee Department of Agriculture, Bugwood.org

If you’re wondering if webworms are crawling in your trees, look for the following signs:

  • Webs around leaves at the ends of branches
  • Larvae, excrement, dried leaf fragments in webs
  • Jerking movements in webs
  • Defoliation (premature removal of leaves)
  • Caterpillars on trees and shrubs

People often confuse this tree worm with Eastern Tent Caterpillars, which appear in early spring. You can see which bug has infested your tree by locating their nests. Are they in the crotches of branch limbs or at the ends of the branches? If it’s the latter, you’re looking at Fall Webworms.

Treatment: How do you treat webworms?

Water hoses: You can spray the nest with a water hose which will knock the nest down the tree. This is an environmentally friendly approach as it allows nature’s food chain to take care of the webworms by giving birds and other predators a good snack.

It’s important not to just toss the nests aside as caterpillars can still climb their way back to the tree.

If you’re worried about the fall webworms in your landscape and would like to take advantage of one of our programs (Canopy Protection Program or a specific Intensive Program) to address your concern, contact us to meet with a Certified Arborist.

Check out our blog post from 2017 for more information on this seasonal pest.

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