Well, if they started the Death March, you could spray the whole circle with soapy water. That's what animal ctrl does for killer bees to quickly kill them. Cuts off the air supply for the abdominal breathing holes. Ants breathe similarly, I believe. One mass death.
Maybe I'm just a sadist. No bugs are allowed to live in my house, except web-building spiders, and centipedes, because (though I hate them) they kill/eat the hunting spiders who roam about.