Adults are about 1/8 inches long. Their body is laterally flattened and is brownish-black to black. They have a reddish back when they are full of blood. They have no wings and hop when they move. Mature larvae are about twice the size of an adult in length. Larvae are whitish, slender, eyeless, and legless. They do have well-developed heads. It is not necessary to have pets in the house since your blood will do. Fleas can jump about 6 inches vertically. Many people who leave their homes for an extended amount of time are unaware of the few adult fleas present. They are often greeted and severely attacked by fleas upon their return. this can occur even if the building has been vacant of animals and humans for as long as 6 months. This situation can occur because of the potentially long pupal period. Adults can live for months without food, and because fleas have not been removed via normal vacuuming.