 You are entering and exiting your house, and that is when flies will also come in and out of your house. What attracts them? They don't smell. What attracts the flies to them? To inside your home? No, to the trap itself. I'm sorry. Oh, yeah. So it's all seed grade attractants in there, the ingredients. It mimics what they either like to breed in or what they like to eat. Okay. All right.