hmmm chunked by what??? an animal probably would have eaten the whole top, so probably grasshoppers or inchworms, you could spray with bug repelent, seven dust is good for slugs and fungus gnats and stuff, mild soap solution sprayed on the leaves is supposed to help. usually i just let them be unless i think they are in danger of taking over the plant, be wary of spraying poison on a plant you plan to smoke in the futer.