Several species have invaded houses, originally because tropical houses were not that much different from the outside, but perhaps had a richer food supply. They have spread with the movement of people throughout the world, and are able to live in the temperate zones, because of the warm situation which humans maintain in their houses. In houses, they get it to food to eat it and destroy more by fecal contamination . The Blattidae including American cockroach, Periplaneta americana . All produce characteristic odors, and many experienced pest control person can tell species infesting house from the smell.
All cockroaches lay eggs in clusters, glued together within an ootheca .
One important group of cockroaches which is not economic pests, are a group of wood roaches which live in decaying logs in social groups, several generations together. Newborn cockroaches obtain these microorganisms by feeding on the cast skins of older siblings. Probably roaches like these were the direct ancestors of termites. Prothorax greatly lengthened, the coxae very long, front femur and tibia armed with long spines for grasping prey. Heads highly movable, mantids are the only insects which can look over their shoulder .