Fleas extract and consume the blood of host animals in order to survive. Neither cat nor dog fleas leave the host voluntarily and will typically remain with one host throughout their lifespan. However, if dog fleas are forcibly removed from their host, they will locate a new host or return to the original host if possible.
The life cycle of the flea is composed of the egg, larval, pupal and adult stages. Cycle length ranges from several weeks to several months and is largely dependent upon environmental conditions. Fleas lay between four to eight eggs after a meal, with the highest concentrations of laying occurring within the last few days of the female’s life. Unlike the eggs of some other parasites, flea eggs are not sticky and usually fall to the ground immediately upon being laid. Flea eggs hatch into larvae within one to 12 days. Flea larvae are approximately 3 to 5.2 mm long and are semitransparent white in color. The larval stage lasts from four to 18 days, after which larvae spin silken cocoons and enter the pupal stage. The pupal stage may be complete within three days, or it can last as long as one year.
Adult fleas begin searching for food when they emerge from the pupal stage. While fleas are noted for their jumping abilities, they will remain stationery when a suitable host is located. Females begin laying eggs within 48 hours of the first feed, thus beginning the life cycle again.