Bed bugs, tiny little rust-colored insects of the Cimicidae family, live by feeding on the blood of humans and other warm-blooded hosts. They get their name from their favorite habitat: mattresses (they like sofas and other cushy furniture, too). Bed bugs are most active at night, just when you’re asleep in your bed and easy prey. While their bites can be itchy, bed bugs are more of a nuisance than a health threat at this point.