Last year my Brussels sprouts were decimated by the same type of worm that attacks broccoli. While my broccoli did sustain some damage, the Brussels sprouts were wiped out. What can I use to combat these critters? Hot pepper spray? Vinegar? I do try to follow organic practices. Thanks. I have more photos if you need more.
I think this is cross-striped cabbageworm. I don't know when the adults fly, but covering the plants when they are active would prevent them from laying eggs. You can use insecticides that contain BT (Bacillus thuringiensis), which is a bacterial spore that only affects caterpillars. It is a very safe material. You treat the plant...it isn't a contact insecticide, the caterpillars have to eat the BT.