Fall Webworm

Yesterday, I came across a small Fall Webworm (Hyphantria cunea, family Erebidae) nest on a Callery pear (Pyrus calleryana) in southwest Ohio. The webworms were the black-headed biotype, but more on that later.

Fall Webworms (Hyphantria cunea, family Erebidae) have been virtual no-shows over much of Ohio this season. Although, there are reports of highly localized populations with noticeable nests, trees in much of the state are largely free of silk webbing.

This is the second posting on Fall Webworm this season. The first Alert posted on July 27 noted that fall webworm nests are late, but on the rise. However, several significant developments have occurred since that time.

Fall Webworm (Hyphantria cunea, family Erebidae) nests are becoming noticeable in southwest Ohio. Their arrival seemed to be unusually late this season until close inspections revealed the nests are housing the red-headed biotype. But more on that later.

Fall Webworm (Hyphantria cunea) has two overlapping generations per season in Ohio. The "fall" in the webworm's common name is based on the moth caterpillars becoming more apparent late in the season due to larger second-generation nests than those produced by the first generation.

Overwintered fall webworm (Hyphantria cunea) eggs have hatched in southwest Ohio and first-generation nests are becoming noticeable. Look for these hairy caterpillars inside small silk nests enveloping just a few leaves. The nests will rapidly expand over the next few weeks to include more leaves and become far more evident.

Fall Webworm (Hyphantria cunea) has two overlapping generations per season in Ohio. The "fall" in the webworm's common name is based on large second-generation nests normally appearing late in the season. However, we are receiving reports that where localized webworm populations are high, the caterpillars are already producing some truly spectacular nests sometimes enveloping entire trees.

Overwintered fall webworm (Hyphantria cunea) eggs are hatching and first-generation nests are appearing in southwest Ohio. Look for these hairy caterpillars inside small silk nests enveloping just a few leaves. The nests will rapidly expand over the next few weeks to include more leaves and become more evident.

Participants at yesterday's Greater Cincinnati BYGLive! Diagnostic Walk-About observed second-generation Fall Webworm nests on a number of hosts including baldcypress. All of the nests were relatively small and populated with 1st or 2nd instar caterpillars.

First-generation nests of the deceptively named fall webworm (Hyphantria cunea) are now becoming evident in Ohio. This native moth has two generations per season in Ohio with the first-generation appearing once the overwintered eggs hatch.