Sorry to hear this, Terry – hibiscus sawfly are the worst! They can be treated with pesticides, if you are so inclined, but if not, the best thing to do is to handpick them, or cut off leaves that are showing heavy damage. Their damage is easy to recognize as it is quite distinctive. It can be a bit more difficult, however, to recognize the larvae themselves, as sawfly larvae turn the exact color of the plant they eat. But once you train your eye to recognize them, you can pick them out more easily.