I have one. It’s fun. But it doesn’t kill the fly. It will knock a fly out, reliably. Often they are on their backs twitching their wings, and you have to finish the job with a piece of tissue paper. So, a big cucaracha? I doubt it would do anything from across the room. It might not even do much if you point blank try to execute the cockroach with a shot directly to the head. You should buy one and find out!
