In Georgia last week I found severe damage by hibiscus sawfly. Larvae and adults were present on the plants I surveyed. The adults are active throughout the summer. The larvae feed on hibiscus and related plants. The larvae skeletonize leaves when they are young but quickly defoliate plants as they grow. Contact insecticides such as bifenthrin and orthene will kill larvae. Other insecticides such as spinosad, acetamiprid, azadirachtin and other listed here can also be used. They are not caterpillars so be sure to look for sawflies specifically on the label of the product you select. More information on this critter is here.