Walking to school today I found a nice infestation of azalea caterpillars (Datana major). These are one of our largest and most colorful caterpillars. They are light green right after hatching. A little older and they get yellow and black stripes from head to tail (?). The largest stages are shiny black with rows of yellow spots. For such a bright creature they can be awful hard to see. The easiest way to find them is to look across the top of azalea bushes for twigs with no leaves. It will look like some passerby grabbed a twig in their fist and stripped all the leaves as they walked. Once you find this feeding damage poke around and the caterpillars will be right there. Azalea caterpillars and many other species curl into a ‘C’ shape when they are scared. This must scare off some predators but don’t be frightened. Azalea caterpillars don’t have any sharp spines or urticating hairs (but they may regurgitate some yellow juice on your hand).
Azalea caterpillars feed on Rhododendron spp. and blueberries so don’t worry about other plants in your yard. If you have an unusually large infestation they could defoliate a plant otherwise they will strip the leaves off a branch or two. There is no reason for homeowners to get out the insecticide for this pest. Azalea caterpillars are gregarious and it is easy to spot where they are feeding. On an average azalea bush you could pick off and destroy all the caterpillars in few minutes if necessary. Plants can be pruned to remove damaged branches or branches full of caterpillars. Information about caterpillar management for professionals is here.
These caterpillars are beautiful and pretty common this time of year. If you have an azalea (trust me you probably do) it is worth a look. Go find one!