Azalea caterpillars can be active this time of year. The following is more information.
The female Azalea caterpillar moth lays clusters of eggs on the underside of leaves, and caterpillars feed gregariously. Early instars appear red with four white to yellowish longitudinal lines down each side. Older larvae have read heads, red legs, and black bodies with white to yellowish 'broken' longitudinal lines down each side. This gives older larvae a spotted appearance. Young caterpillars skeletonize leaves, and as larvae age, they consume entire leaves. Caterpillars will raise both ends off of leaves when disturbed, thus displaying a C shape. Control options when larvae are small include Bacillus thuringiensis (kurstaki), Conserve SC, Sevin, or pyrethroid insecticides.
Azalea caterpillars in mass. Photo by Arnold T. Drooz, USDA Forest Service, Bugwood.org
Information from a past issue of the UD Ornamentals Hotline Newsletter.