Fall Webworm

Fall Webworm has two generations per season in Ohio. The "fall" in the webworm's common name is based on the appearance of second generation nests late in the season. The first generation began to appear in southern Ohio in late May (see, "Spring, Summer, Fall Webworms," June 13, 2018) and second generation caterpillars are now on the scene.

First generation nests of the deceptively named Fall Webworms are now becoming evident in Ohio. One of the most common question that I get about these moth caterpillars is, "why are they called "fall webworms" when it's not fall?"

Southern and central Ohio do not appear to be experiencing an "outbreak" of our native fall webworm (Hyphantria cunea) this season.  However, I'm seeing some relatively high localized populations and this lead to a surprising discovery of red-headed webworms in southwest Ohio.

As Jim Chatfield and I wandered through the “Crablandia” plot evaluating and photographing crabapples today, we noticed multiple stages of the fall webworm munching on some of the foliage of the trees.  We first noticed the initial stages of the fall webworm caterpillars, which were small enough to have congregated on a single leaf.

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First generation fall webworms (Hyphantria cunea) are appearing in central and southern Ohio.  Fall webworm moths typically have two generations per year in Ohio and despite their common name, first generation nests usually appear in late spring.  Fall webworm caterpillars only feed on the leaves that are enveloped by their silk nest.  As caterpillars grow in size, they expand their nest by casting silk over more leaves to accommodate their expanding appetites.

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