Cat fleas are the most common ectoparasite on domestic cats and dogs. Dog fleas look like cat fleas but are rare in California. Sticktight fleas, are commonly found on ground squirrels and poultry; the females firmly attach themselves along the ears and eyes of their host. They can become a problem with pets that roam. The ground squirrel flea is found on ground squirrels and is the vector of sylvatic plague in California. However, fleas on cats or dogs in California most likely are cat fleas.
Adult fleas are no larger than 1/8 inch long, so it is difficult to see a number of the characteristics used to describe them. These reddish-brown, wingless insects are laterally compressed, so they look as if they are walking on edge. Cat fleas have both pronotal and genal combs. They have piercing-sucking mouthparts through which they obtain blood meals from their hosts.