What a baby flea looks like depends on which of three pre-adult life stages you call the "baby" stage. The flea life cycle has four distinct phases -- the egg stage, the larval stage, the pupal stage and adulthood. Fleas are parasitic bloodsuckers only in their adult stage. In their other stages, they're generally found not on hosts but in their bedding and other favorite lounging spots.
Adult female fleas lay an average of 27 eggs a day, according to Texas A&M University. Flea eggs are not sticky; they are dry and smooth. They tend to slide off the hair of host animals -- so they're usually found scattered in your pet's bedding. Flea eggs are extremely tiny, typically measuring 0.05 millimeter in length. You will have a very difficult time seeing them with your naked eye, though.
Within 12 days of being laid, flea larvae emerge from eggs. Flea larvae are between 3 millimeters and 5.2 mm long. Flea larvae are wormlike, white and semi-transparent, but they darken as they grow because they feed primarily on adult flea feces. Fleas will stay in the larval stage between four and 18 days. During this time they have three molts or instars. During the third instar, they begin to create cocoons.
Flea larvae make their cocoons by secreting a silky substance and binding it to materials in their environment, helping them to camouflage themselves. Their coverings are lumpy, crusty and irregularly shaped. The pupal stage can last between three days and one year. Pupae do not emerge from these cocoons until they know a host is near, sensing them from vibrations or carbon dioxide.
Adults, Feeding and Flea Dirt
Fleas emerge from the pupal stage as adults. They seek hosts and begin feeding on their hosts' blood. They can survive in bedding and carpeting as long as host animals are available to feed on. They shed reddish-black waste that could wind up on your pet's bedding -- don't mistake this feces, or flea dirt, for pupae, eggs or larvae. Smear a fleck of it on white paper -- does it turn reddish or rusty? Your dog has fleas.