Fall webworms form a tent on a tree at Hartman Creek State Park in Waupaca County, August 2026. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942

The native insect known as fall webworm (Hyphantria cunea) has been generating calls from curious property owners over the past few weeks.

The caterpillars don’t draw much attention on their own. Instead, what catches the eye at this time of year are the large webs (or “tents”) that they create on the tips of tree branches, giving them a protected feeding site. The webs have been present for at least one month but weren’t very noticeable when they were only a few inches long.

Fall webworms feed inside a tent. Thanks mostly to the timing of their feeding cycle (in the fall), the insect is generally not a threat to tree health. / Photo Credit: Wisconsin DNR

These insects and their webs become large in late summer and early fall, when trees have passed their peak period of food production (“photosynthesis”) and often start to shut down for the season. Because of that, the insects’ impacts on the tree are usually minimal and there is no need to remove the nests and caterpillars unless they are a visual nuisance. Wind and rain will usually break up webs within a few months.

Property owners who want to remove a visually undesirable nest can break it up with a stick and spray insecticide, break it up and leave the caterpillars exposed to natural enemies, or put on rubber gloves and drown the nest in a bucket of soapy water. There is no need to prune the branch off the tree.

It should be noted that these caterpillars are a different species than other insects known as eastern tent caterpillar, forest tent caterpillar and spongy moth. Those caterpillars emerge in spring, and each can cause substantial damage to trees.

The DNR provides a Forest Health fact sheet on fall webworm.