Once the flea emerges form the cocoon, it immediately begins seeking a host. A flea that emerges from the pupael cocoon due to the pressure of the pet stepping on it, can hatch, jump on the pet as it is walking by, and begin feeding in as little as 7 seconds. There is nothing currently available that is able to prevent the flea from jumping on the pet and feeding due to the short time frame involved. There are no repellents for fleas. Contrary to some myths, fleas are not repelled or killed by such items as garlic or brewers yeast. In laboratory experiments fleas were fed brewers yeast in order to sustain them until a blood meal could be introduced. There is also no clinical data to support theory of sonic flea control devices. Owners that experience success with these types of treatments are usually the lucky few that would not suffer from fleas regardless of what the pet is on. Newly emerged fleas are attracted to pets by various stimuli produced by these hosts: body heat, movement and exhaled carbon dioxide. In contrast to larvae, adult cat fleas will orient and move towards light. The adult is negatively geotactic (prefers to move upward). These behaviors enhance the cat flea's success in finding a host because newly emerged fleas move directly to the top of the carpet pile where they are more likely to encounter a passing host. The presence of fleas is not an indication of a "dirty" home. Regardless of sanitary conditions a flea is able to survive in a home as long as there is a host on which to feed.

If the newly emerged cat flea does not find a host, it can survive for 1 to 3 weeks before requiring a blood meal, but once they initiate feeding the flea must be able to feed again within 4 days or it will die.

Adult fleas are dark reddish-brown and 2 to 5 mm long. They have thin, flattened bodies and backward-directing spines on their legs and bodies that facilitate forward movement through fur, hair or feathers and prevent them from being easily dislodged.

Adults make up only about 5% of a population. Fleas are wingless, but have strongly developed legs that permit them to jump up to 100 times their own body length (8 inches vertically and 15 inches horizontally). That's the equivalent of a human jumping the length of three football fields. The g forces (gravity pull) on the flea measure about 150g's as it jumps. Compare that to the g force of 3 that astronauts experience as the space shuttle takes off. Fleas are very resilient in their environment due to their strong insect exoskeletons made up of a substance called chitin (KITE-IN). It is this shell that helps the flea survive on the pet. Once on a host, the cat flea initiates feeding within seconds and egg production begins within 48 hours. Contrary to what has been commonly reported, the adult cat flea is actually a permanent ectoparasite. It does not leave the host unless it is forced off.

Therefore, once on a suitable host, fleas do not leave their host voluntarily. They remain until removed by ingestion, grooming behavior, dying a natural death, or dying from chemical induced death (insecticide application). The drawback with any adulticide only treatment is the 85% of the pre-adults waiting to develop in the environment. The adult cat flea can survive on the host and maintain some reproduction for 2-4 weeks under most natural conditions, but if not killed prematurely an adult flea may live as long as 4 months.