Fleas are parasitic insects which are found all over the world. They feed on the blood of cats, dogs and other animals, including humans. Fleas in cats and dogs are normally one of two species, either Ctenocephalides felis, the cat flea, or Ctenocephalides canis, the dog flea. However neither is host specific, and while the cat flea can infest dogs and vice versa, both can infest humans. In fact, cat fleas are the most common fleas on both cats and dogs and have been known to infest more than 50 different animals, including raccoons, weasels, opossums and badgers. There are also human fleas, rat fleas (which were responsible for spreading the bubonic plague), rabbit fleas and many more. Fleas go through four different life stages. The adult phase is the only stage seen on pets, while the other stages are found in the environment, usually in carpets or bedding and also in the yard. Adults are usually between 1/16th to 1/8th of an inch long, red-brown in color and have three pairs of leg