It's more than likely caterpillars. They are out and about right now taking the tops off a bunch of my OGs..check and see if there's any black spots on the leaves or near the dead buds. If so, spray BT stat.
I guess I've got low standards. I get the ultimate revenge. If the weed has a touch of mold and mites and maybe a caterpillar or two I smoke or BHO the little horrors or at least give it to someone who doesn't really care. Chit in the olden days you could break a brick of Mexican brown weed in half and there would be a cloud of mold and under a microscope it had more wildlife than the zoo.
I am surprised that's Caterpillar damage and not botrytis. Just hit it with some Clordaine or myathalon. that'll fix them.