The Purdue Plant and Pest Diagnostic Laboratory

P&PDL Picture of the Week for
September 19, 2005

Yellow Wooly Bear Caterpillars

Cliff Sadof, Extension Ornamental Entomology Specialist, Purdue University

Late in the summer brings its share of late season caterpillars showing up on trees. This late in the year most of these caterpillars have almost completed their feeding and are unlikely to cause any damage to the tree. The caterpillar in this photo, the yellow woolly bear (Spilosoma virginica) were found on black walnut. When one of these caterpillars were brought into the lab, the larva of a parasitic wasp emerged out of the abdomen, and weaved a cocoon.

Click here for information on the Annual Wooly Worm Festival in Banner Elk, NC

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Parasitized larvae
Photo courtesy of John Obermeyer, Purdue University

Yellow woolly worm on black walnut
Photo courtesy of Guillermo Padillo

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service