The Flea

Dec 07, 2008 Features / Columnists, Interesting Creatures in Guyana

Flea is the common name for any small wingless insect of the order Siphonaptera. Fleas are said to be 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.

Fleas are small, measuring about 1.5 to 3.3 millimetres in length. They are said to be very agile, are usually light brown to mahogany in colour, and are wingless insects with tube-like mouthparts adapted to feeding on the blood of their hosts.

Their bodies are laterally compressed, 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)) – around 200 times their own body length, making the flea one of the best jumpers of all known animals (in comparison to body size), second only to the froghopper.

The flea’s body is hard, polished, and covered with many hairs and short spines directed backward which also assists its movements on the host.

Its tough body is able to withstand great pressure, likely an adaptation to survive scratching and other forms of assault.

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 a match or lighter. However, reports state that they are susceptible to drowning.

Fleas lay tiny white oval shaped eggs and their larvae are small and pale with bristles covering their worm-like body. They are without eyes, and have mouthparts that are adapted to chewing.

While the adult flea’s diet consists solely of blood, the larvae feed on various organic matter, including the faeces of mature fleas.

In the pupal phase, the larvae are enclosed in a silken, debris-covered cocoon. Fleas are holometabolous insects, going through the three life cycle stages of larva, pupa and imago (adult).

The flea life cycle begins when the female lays after feeding. Adult fleas must feed on blood before they can become capable of reproduction.

Eggs are laid in batches of up to 20 or so, usually on the host itself, which easily roll onto the ground. As such, areas where the host rests and sleeps become one of the primary habitats of eggs and developing fleas. The eggs take around two days to two weeks to hatch.

Fleas attack a wide variety of warm-blooded vertebrates including dogs, cats, humans, chickens, rabbits, squirrels, rats, ferrets, and mice.

They are in fact a nuisance to their hosts, causing an itching sensation which in turn may result in the host attempting to remove the pest by biting, pecking, scratching in the vicinity of the parasite.

Fleas are, however, not simply a source of annoyance. Some people and animals suffer allergic reactions to flea saliva resulting in rashes, and their 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 of two bites, and can remain itchy and inflamed for up to several weeks afterwards.

Fleas can also lead to hair loss as a result of frequent scratching and biting by animals, and can cause anemia in extreme cases. Besides the problems posed by the creature itself, fleas can also act as a vector for disease.

For example, fleas transmitted the bubonic plague between rodents and humans by carrying Yersinia pestis bacteria. Murine typhus (endemic typhus) fever, and in some cases Hymenolepiasis (tapeworm) can also be transmitted by fleas.

The itching associated with flea bites can be treated with anti-itch creams, usually antihistamines or hydrocortisone. Calamine lotion has been shown to be ineffective for itching, while their attack on animals can be controlled by dousing them, their larvae or their eggs with insecticides.
(Source: Wikipedia the Free Online Encyclopedia)