How to Stop Fall Webworm Damage to Your Trees

It's that time of year again when the trees turn colors and you can spot large webs of worm-like insects crawling around inside. What are these things, and why do they appear all over the trees? Even worse, are they killing the trees and should you be worried?

What are Webworms?

These insects are known as fall webworms, a type of moth that lays eggs on tree leaves, which then hatch as caterpillars. They form webs on hundreds of different tree species throughout North America and the world and start to appear around June in some states and can extend through October.

There are two types of fall webworms: black-headed and orange-headed. The orange-headed fall webworm only produces one generation per year whereas the black-headed webworm can produce two.

The webs are formed on the tips of branches and can spread as the caterpillars hatch, grow and consume the surrounding leaves. It takes about 70 days for the webworms to go from eggs to the pupal stage, in which they leave the web and overwinter at the base of the tree.

How to Get Rid of Webworms

Though the webs are unsightly, there's no real damage to worry about. Yes, the webworms will consume the leaves but not enough to kill the tree. However, there are times when you should take action against the webworms, such as on trees that have not fully developed.

Most trees have stopped growing when the fall webworm does its most damage, which is the hottest part of the summer. Their damage is mostly considered aesthetic. Elder trees can take the brunt of damage from the caterpillars, but underdeveloped pecan and fruit trees may require assistance against the pests.

One way to control these fall pests is to use an insecticide formulated for webworms, bagworms and similar leaf-feeding caterpillars. Something like DiPel Pro could work well as it contains Bacillus thuringiensis as the active ingredient. It's a naturally occurring bacterium that attacks and kills the caterpillars starting within hours of application in some cases.

Webworms and Similar Caterpillar Pests

Fall webworms are sometimes mistaken for eastern tent caterpillars and bagworms. Tent caterpillars also form in webbed nests and have been known to defoliate entire trees. However, the trees usually bounce back with new leaves the following year.

Bagworms are a more serious pest and form in bag-like nests. They build up rapidly on trees and cause severe defoliation. They attack everything from apple trees to willows and sycamores. Using bifenthrin and similar pyrethroid products can help to kill and control these pests.

Serious Pest Control from Heritage PPG

When fall webworms and similar pests attack your trees, fight back with pest control products from Heritage PPG. Whether you want a synthetic insecticide or a biological solution for the problem, we have a huge inventory of products to help keep your trees protected from invasive caterpillars and to reduce their damage throughout the season.

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