Young caterpillars feed in a cluster side by side unless disturbed. These first instar caterpillars are approximately 3/8 inch long after feeding for eight to ten hours. They remain gregarious and soon devour the entire leaf.
As the larva matures, it becomes highly colored. The mature caterpillar is yellow with seven red longitudinal stripes and a black head. Now the caterpillar is about two inches long, and predominately black, with a red last segment and eight broken yellow (occasionally white) lengthwise stripes. The head and legs are mahogany-red. View the azalea moth here!