Flea

Flea is the common name for any of the small wingless insects of the order Siphonaptera (some authorities use the name Aphaniptera because it is older, but names above family rank need not follow the ICZN rules of priority, so most taxonomists use the more familiar name). Fleas are external parasites, living by hematophagy off the blood of mammals and birds. Genetic and morphological evidence indicates that they are descendants of the Scorpionfly family Boreidae, which are also flightless; accordingly it is possible that they will eventually be reclassified as a suborder within the Mecoptera. In the past, however, it was most commonly supposed that fleas had evolved from the flies (Diptera), based on similarities of the larvae. In any case, all these groups seem to represent a clade of closely related insect lineages, for which the names Mecopteroidea and Antliophora have been proposed।

Some well known flea species include:
Cat flea (Ctenocephalides felis),
Dog flea (Ctenocephalides canis),
Human flea (Pulex irritans),
Northern rat flea (Nosopsyllus fasciatus),
Oriental rat flea (Xenopsylla cheopis)।

Morphology and behavior

Fleas are small (1/16 to 1/8-inch (1.5 to 3.3 mm) long), agile, usually dark coloured (for example, the reddish-brown of the cat flea), wingless insects with tube-like mouthparts adapted to feeding on the blood of their hosts. Their bodies are laterally compressed (Human anatomical terms), permitting easy movement through the hairs or feathers on the host's body (or in the case of humans, under clothes). Their legs are long, the hind pair well adapted for jumping (vertically up to seven inches (18 cm); horizontally thirteen inches (33 cm)[1]) - around 200 times their own body length, making the flea the best jumper of all known animals (in comparison to body size)।

The flea body is hard, polished, and covered with many hairs and short spines directed backward[2], which also assists its movements on the host। Its tough body is able to withstand great pressure, likely an adaptation to survive scratching etc. Even hard squeezing between the fingers is normally insufficient to kill the flea; it may be necessary to capture them with adhesive tape, crush them between the fingernails, roll them between the fingers, or put them in a fire safe area and burn them with match or lighter. They can also be drowned।

Fleas lay tiny white oval shaped eggs. Their larvae are small and pale with bristles covering their worm-like body. They are without eyes, and have mouthparts adapted to chewing. While the adult flea's diet consists solely of blood, the larvae feed on various organic matter, including the feces of mature fleas.[3] In the pupal phase the larvae are enclosed in a silken, debris-covered cocoon.