Azalea Caterpillar

Adult azalea caterpillar moth
(photo by James Baker)

The azalea caterpillar, Datana major G & R, is found in Florida from July through October on azaleas. Often, the caterpillars completely defoliate much of the plant before they are detected. So, take a good close-up look at your azaleas right now! While the caterpillar appears hairy, it is harmless to humans and can be picked off the bushes by hand.

The caterpillar is found in Florida as far south as Polk and Hillsborough Counties and azaleas are the only known hosts in Florida.

Eggs are deposited by the female moth in late spring in masses of 80 to 100 on the underside of the leaf. 

azalea caterpillar (UF photo)

The first instar caterpillars feed in a cluster side by side unless disturbed. The 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.   

The first instar caterpillar is yellow with seven red longitudinal stripes and a black head. As the larva matures it becomes highly colored. The mature 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.

The adult moth is light brown with a wing expanse of 1 3/4 inches. 

The semi-skeletonized leaves dry up, turn brown, and remain on the plant for several days. If disturbed some of the caterpillars drop one or two inches below the infested leaf and hang by a silken thread. When it is disturbed, the caterpillar raises its front and rear ends into the air. Young larvae skeletonize the leaves and the larger ones eat the entire leaf. In some parts of the South there may be a partial second generation, but one generation is usually the rule. It is thought to overwinter in the pupa stage.

Severe damage by azalea caterpillar
(photo by D Shibles)
 

Healthy azalea (photo by D. Shibles)

Most of the damage in the southeast United States occurs in August and September, but in Florida it continues through October. This caterpillar is pretty easy to control with commonly available pesticides such as Bug-Be-Gone Max (bifenthrin), Sevin (carbaryl), Orthene Insect Killer (acephate), Permetrol (peremethrin) and several others. More environmentally friendly products include Thuricide and Dipel (B.t. containing products) and Conserve (spinosad).

This time of year carefully inspect your azaleas for this pest. The caterpillars often go unnoticed until the damage is quite severe. Do not prune off branches with no leaves as the leaves will grow back in a few weeks. Any pruning at this time of the year will result in a loss of flower buds which are already forming on the leaf-eaten branches.