Cat and dog fleas can be found in the same area. They are very similar in appearance. They are small, 1/8-inchlong, wingless, laterally flattened and have piercing-sucking mouthparts. The flea has very well developed legs allowing it to jump at least six inches straight up. They are black-to-reddish brown in color. Its body is covered with backward projecting spines, which help it to move between the hairs on the host animal. The head of the female cat flea is twice as long as it is high; the head of the female dog flea is less than twice as long as it is high. Both cat and dog fleas have a row of very heavy spines on the front of the head and the back part of the first body segment. Cat and dog flea larvae are 1/4-inch long when fully developed. They look much like fly maggots except for their well-developed heads. They have 13 body segments and are dirty white in color with backward projecting hairs on each body segment. They have a pair of hook-like appendages on the last abdominal segment.
Cat and dog fleas undergo complete metamorphosis. After each blood meal, females lay four to eight eggs at a time (but 400 to 800 total within her lifetime) on the host animal and/or in its bedding. The eggs fall into the nest and/or bedding of the host animal or wherever the animal happens to be at that time. The eggs hatch in about 10 days, and the developing larvae feed on the adult flea feces, which contain bits of dried blood. Depending on temperature, they molt three times in from seven days to several months. When mature, they spin silken cocoons in which they pupate. The pupal stage lasts up to 20 weeks. The adult cat flea often stays within the cocoon until vibrations stimulate it to emerge. Development requires from 16 days to a year or more.
Adult fleas feed on blood with their piercing-sucking mouthparts. They typically seek a blood meal within two days of becoming an adult. The flea inserts its mouthparts in the skin, injects saliva, and sucks blood. The bite leaves a red spot on the skin. The saliva is irritating to the host, causing dermatitis and hair loss in allergic animals. Cat and dog fleas prefer these two animals but readily feed on other animals. Adult fleas remain on the host animal throughout their lifetime but are occasionally knocked off the animal by scratching. Occasionally, they can be found in the pet bedding and resting area. Wild animals nesting in structures initiate indoor flea populations. Larvae typically are found in areas where pets spend most of their time as well as in animal nesting areas.