Flea is the common name for any small wingless insects. Fleas are external parasites, living by hermatophagy off the bloods of mammals and birds.
Fleas are small, 1.5mm to 3.3mm long, agile, usually dark coloured, wingless insects with a tude-like mouthparts adapted to feeding on the blood of their hosts. Their bodies are laterally compressed (i.e. flattened side to side) permitting easy movement through the hairs, or feathers, on the hosts body. Their legs are long, the hind pair well adapted for jumping (vertically up to 18cm); horizontally to 33cm – around 200 times their own body length.
The flea body is hard, polished, and covered with many hairs and short spines directed backward, allowing the flea a smooth passage through the hairs of its hosts. Its tough body is able to stand great pressure, likely an apadatation to survive scratching. Even hard squeezing between the fingers is often insufficient to kill the flea. It may be necessary to crush them between the fingernails.
Fleas lay tiny white oval shaped eggs. Their larvae are small and pale with bristles covering their worm like body.
Fleas attack a wide variety of warm-blooded vertebrates including humans, dogs, cats, chickens, rabbits, rats and mice. Fleas are a nuisance to their hosts, causing an itching sensation which in turn may result in the host attempting to remove the pest by picking and scratching at the vicinity of the parasite.
Flea bites generally result in the formation of a slightly-raised swollen itching spot with a single puncture point at the centre. The bites often appear in clusters or lines, and can remain itchy and inflamed for up to seeral weeks afterwards.
Pictured above are flea bites.