Hello, 

Those are actually not caterpillar but are sawfly larvae.  It look like it might be from the Genus Monostegia.  They tend to be short lives and should be gone in a few weeks with plenty of time for your plant to regrow leaves so you can just leave them alone.  If they are really bother you, you can hand pick them off.  Since they are not caterpillars they are not controlled with Bacillus thuringiensis (Bt). You could try using  insecticidal soap but due tot their size they might be to large for it to be effective. 

As a last resort, chemical options include: spinosad, acephate (Orthene), bifenthrin, carbaryl (Sevin), malathion and permethrin. Make sure if you do use a chemical that you read and follow the label. 

- Emily