Rats have well-developed senses of taste, smell, and touch. They have a keen sense of hearing, often using ultrasound to communicate, and are particularly sensitive to any sudden noise. Both species reproduce quickly and become sexually mature in about three months. Each female can produce 4 to 6 litters and between six and eight young in a year. Rats must gnaw to keep their teeth, particularly their constantly growing incisors, worn down. They damage woodwork, plastic, brick, and lead pipes, and strip electrical cables.
Rats can cause a great deal of structural damage. They can cause serious fires by gnawing through insulation around electrical wires, flooding by puncturing pipes, and even death by chewing through gas lines. The insurance industry estimates that damage caused by rodents to wiring accounts for 25% of all electrical fires in buildings.