Hibiscus sawfly, Atomacera decepta, is a common pest of hibiscus. Not much is known about this critter from what I can find. A report from Connecticut indicates the life cycle is about 28 days. Yesterday I found adults and young larvae on hibiscus shrubs at J.C. Raulston Arboretum in Raleigh. Adults are black with orange on their thorax. There was not much damage yet and I found Japanese beetles on the same shrubs. However, hibiscus sawflies can defoliate some hibiscus species and cultivars. There is a difference in susceptibility though because I know which shrubs in the Arboretum I can walk to to find the sawflies and which never have them. A paper in Journal of Environmental Horticulture outlines some differences in genotype susceptibility. If you love hibiscus, choosing resistant varieties is a good strategy. Otherwise you will have yearly battles to save you hibiscus or yearly disappointment when it gets hammered by sawflies. Sawflies are not caterpillars they are hymenopterans, the same order as bees and wasps. Thus, if you are looking for an insecticide option it should specify sawflies on the label.