Cockroaches live in a wide range of environments around the world. Pest species adapt readily to a variety of environments but prefer warm conditions found within buildings. Many tropical species prefer even warmer environments and do not fare well in the average household.

Cockroaches leave chemical trails in their feces, as well as emitting airborne pheromones for swarming and mating. These chemical trails transmit bacteria onto surfaces. Other cockroaches will follow these trails to discover sources of food and water, and also discover where other cockroaches are hiding. Thus, cockroaches can exhibit emergent behavior, in which group or swarm behavior emerges from a simple set of individual interactions.

Research has shown group-based decision-making is responsible for complex behaviors such as resource allocation. In a study where 50 cockroaches were placed in a dish with three shelters with a capacity for 40 insects in each, the insects arranged themselves in two shelters with 25 insects in each, leaving the third shelter empty. When the capacity of the shelters was increased to more than 50 insects per shelter, all of the cockroaches arranged themselves in one shelter. Researchers found a balance between cooperation and competition exists in the group decision-making behavior found in cockroaches.

American cockroaches are the largest cockroaches that invade homes. Adults can be slightly more than 2″ long. Adult American cockroaches are reddish-brown or mahogany-colored. The area behind their head is outlined with a yellow band. Immature American roach nymphs are grayish brown. As they mature, their color becomes more reddish-brown. Both male and female American cockroaches can fly. The wings develop when the roaches become adults.

American cockroaches normally live outdoors. They prefer warm, damp areas like flowerbeds, and under mulch. In many parts of the United States, people call them “palmetto bugs” because they live on trees. American cockroaches are very common in the sewer systems of many American cities.

American cockroaches enter homes to find water or food. They can easily pass under doors if the weather-stripping is damaged. Basement windows and garages are also common entryways. When American cockroaches enter homes, they often go to bathrooms, kitchens, laundry rooms, and basements.

Outdoors, American cockroaches eat leaves, tiny wood particles, fungi, and algae. They also eat small insects. Indoors, American cockroaches forage under appliances, in drains, in kitchen cabinets, and on the floor. They eat crumbs, scraps of food, and spilled food that they find. They will also eat pet food that is left out overnight.

There are some cockroach species that can fly well and some that glide from high places. The American cockroach flies, but it's more of a glider. Cockroach species that fly well are Australian roaches, Asian roaches, Smoky Brown roaches, and Pennsylvania wood roaches. Flying roach control is carried out with baits, traps, and spray treatment.