Eggs placed on the pet are not firmly attached and soon fall off. In about a week, the eggs hatch into immature fleas called larvae. Flea larvae are very different from adult fleas. They are wormlike, lack legs, and do not feed on fresh blood, but live on organic matter, including dried particles of blood and excrement voided by the adult fleas. In about 12 days, the larvae are fully grown and change to the pupal stage which then changes into the adult flea.
Adults feed more than once a day on fresh animal blood.
They may live as long as a year and in some cases, even longer. Fleas may be present, though unnoticed, all year in the house but frequently become troublesome following return from a vacation. Fleas inside an empty house soon become extremely hungry. When the vacationers return, they are greeted by these neglected fleas who now make their presence known by biting avidly. Flea bites on humans are generally most prevalent on the ankles and lower portion of the legs.