American cockroach Periplaneta americana takes on a nearly pure white appearance after molting, a process during which insects shed their exoskeletons in order to grow. During this time insects are lethargic and at risk from predators. Reaching 4 centimeters in length, this species is the largest cockroach pest and is found living more often outside homes than in. These cockroaches were introduced to the United States from Africa in the early 17th century and are now common in the southern U.S. and tropical areas. Domestic cockroaches cause billions of dollars of damage every year just in the contamination of food products. What磗 worse, they can cause allergies and carry diseases like dysentery and typhoid.