So where do those larger cockroaches come from? The ones that you see scurrying across the pavement at night or in your garage or in your house. Every house in your city is connected by a storm drain. These storm drains obviously collect water during rainy season, but they store it throughout the year. This allows the roach population to breed exponentially year-round and eventually when it dries out in the summertime or possibly when a drought comes along, they'll scurry out of the storm drain and move into your yard where there's more water and eventually migrate into the house putting pressure inside on the home. Bulwark Exterminating Roach Control.