Q: My azalea had caterpillars clustered at the tip of the limb. Should I spray all plants, or just watch for caterpillars and then spray?
A: Azalea caterpillar, Datana major, is an occasional autumn pest of azaleas. They defoliate random azalea limbs but they will not kill the plant. You can spray them as you see them or simply wait for natural predators to kill them. Hornets and paper wasps find these caterpillars a delicacy.