Fleas are wingless insects and external parasites with mouthparts adapted for piercing skin and living off the blood of mammals and birds. Adult fleas must feed on blood before they become capable of reproduction. Some flea species include the dog flea, the cat flea, the human flea, the moorhen flea, the northern rat flea, and the oriental rat flea. The most common species is the cat flea, which is usually a parasite to cats, dogs, and humans.
Fleas are annoying to their hosts, as their bites cause an itching sensation which may cause the hos, such as a cat or dog, to scratch and bite at the source. Flea bites look a bit like a mosquito bite, a raised round welt with a single puncture wound in the middle. The bites often appear in small clusters of two. Frequent scratching by the animal can also lead to hair loss, and, in extreme cases, anemia.
Treatment for fleas can target fleas at several different life stages. Insecticides are effective at killing fleas in adult, egg, and larvae stages. Flea treatments meant for dogs can be hazardous to cats, and flea and tick ointment can also be hazardous to humans. Therefore, if your pet has fleas or if you suspect they do, visit a vet and carefully follow their instructions.
If you need to learn more about fleas or about combating a flea infestation in your home, check out the links below.
Sources:
http://en.wikipedia.org/wiki/Flea
http://www.pestworld.org/pest-guide/stingingbiting-insects/flea/
