Fleas are small wingless insects, parasitic, when adult, on warm-blooded animals. They are assigned to the order Aphaniytera, whose closest affinities appear to be with the Diptera or two-winged flies. The jaws of the adults are modified for piercing the skin and sucking the blood of the host; the body is flattened sideways, so as to pass readily between hairs. Being without wings is no hindrance to fleas for they have very powerful hind legs which enable them to jump up to 200 times their own length.

Fleas feed on the blood of their host which may be Man, animals or birds. The species which generally attacks Man is Pulex irritans and although it is a nuisance it is not really dangerous. The same cannot be said for the tropical rat flea for it carries the bacillus of bubonic plague which it can transmit to Man in one bite.

Fleas are small wingless insects, parasitic, when adult, on warm-blooded animals. They are assigned to the order Aphaniytera, whose closest affinities appear to be with the Diptera or two-winged flies. The jaws of the adults are modified for piercing the skin and sucking the blood of the host; the body is flattened sideways, so as to pass readily between hairs. Being without wings is no hindrance to fleas for they have very powerful hind legs which enable them to jump up to 200 times their own length.

Fleas feed on the blood of their host which may be Man, animals or birds. The species which generally attacks Man is Pulex irritans and although it is a nuisance it is not really dangerous. The same cannot be said for the tropical rat flea for it carries the bacillus of bubonic plague which it can transmit to Man in one bite.

Not all fleas have eyes. When present, however, the eyes are simple. Fleas also have a pair of short segmented antennae and sharp mouthparts adapted for piercing and sucking. Many fleas can pierce a host's skin and fill themselves with blood in a few seconds.

Fleas lay their eggs in fur, feathers, hair, dust or dry rubbish where they hatch into tiny hairy legless larvae. They feed upon any organic matter or dirt on the floor.

Over a period of four to six weeks they pupate and emerge as adult fleas up to 3 mm in length with hard, shiny, dark skin (but the pupa may lie dormant for periods up to 12 months until stimulated by vibration, e.g. footfalls on floorboards of a previously unoccupied house). On emerging from the pupa the mature flea seeks a host, but is able to live a considerable time even if unable to find one.

They usually breed in warm weather and may reach plague proportions if unchecked. Control of fleas is achieved by strict attention to hygiene, spraying of known infested areas, application of flea powders to birds, poultry and household pets and the extermination of noxious rodents which may carry them.

• There are over 500 species of flea.
• It is noteworthy that fleas do not infest any hoofed animals.
• The best-known species are those found in human dwellings, infesting man, dogs, cats, rats, and mice; but rabbits, squirrels and other animals also harbor them.
• In addition to causing irritation by creeping and biting, fleas are notorious vectors of disease. Several species which infest rats transmit the dreaded bubonic plague from rat to man.
• A curious modification of the ordinary life-history of fleas is shown by the tropical pest called the jigger or chigoe. This flea affects a great many hosts, usually attacking the feet. The female burrows under the skin, mostly of the toes, of man and swells to the size of a pea. Fortunately it is easily extracted by excising the skin.
• If the host dies they leave the body and adopt the first warmblooded animal they come across.
• So-called "performing" fleas are fastened to light objects, which, in their efforts to escape, they pull along. The performance is a high tribute to skilful manipulation by the owner, not to the docility of the fleas, which are incapable of being trained.