Fleas are wingless insects with a mouth evolved for piercing skin and sucking blood. They are an external parasite with over 2000 species in existence across the globe. Fleas are a common problem on domesticated pets and farm animals, but can also thrive on human blood. They feed on a large variety of warm-blooded hosts including cats, dogs, chickens, rabbits, squirrels, ferrets, rats, mice, and of course, humans.. Their bites irritate their host, leaving an itchy red swelling that can persist for several weeks. Their bites cause a swelling not dissimilar to mosquito bites, and on some animals they can lead to hair loss as a result of frequent scratching and biting, and have even been known to cause anemia in some extreme cases. Fleas are a common problem in many Australian households and if you are plagued by fleas you need to get in touch with a pest controller as soon as possible to stop the spreading infestation.