Fall Webworm Moths

You may have noticed white, silken webs covering the ends of tree branches around Old Cahawba. You’re looking at fall webworms (Hyphantria cunea)!

These native caterpillars are easy to spot in late summer and early fall. They feed on many types of deciduous trees, including pecan, hickory, walnut, sweetgum, and fruit trees. Dozens of caterpillars can live together inside their silk webs, which they gradually expand as they consume fresh leaves.

Although their webs can make a healthy tree look alarming, fall webworms usually cause little long-term damage to mature trees. They’re also easy to distinguish from tent caterpillars—fall webworms build their webs around the ends of branches, while tent caterpillars create webs in branch forks.

Fall webworms have a fascinating defense. When disturbed, the caterpillars may shake their bodies together in unison, creating a synchronized “dance” that can startle predators! 

Eventually, the caterpillars leave their webs to pupate in protected places such as leaf litter or beneath bark before emerging as adult moths.

So, the next time you spot one of these spooky-looking webs at Old Cahawba, don’t be alarmed. Those Halloween-like decorations are simply a natural part of the ecosystem!