Order - SIPHONAPTERA
(Greek, siphon = tube; pteron = wing)
Common Name: fleas
Distribution: Cosmopolitan

Description
All fleas are ectoparasites of birds or mammals with mouthparts that are modified for piercing and sucking. The body of the flea is laterally compressed (i.e. flattened from side to side) and enlarged hind legs are modified for jumping. All fleas are wingless. Compound eyes are absent and only simple eyes (ocelli) may be present. Antennae are present but they are extremely short and lie within deep lateral grooves in the head so that they are not readily visible. Antennal structure is a series of short, straight segments (filiform). The legs of fleas are modified with hairs and hooks to grasp the hairs of the host.

Larva
The flea life cycle consists of egg, larva, pupa and adult. The eggs are laid in the host's environment (e.g. nest, kennel, bedding, etc.). Larvae (that resemble fly maggots) develop on material shed from the host, such as skin fragments. A loose cocoon is spun by the mature larva for pupation. Flea pupae can remain dormant for extended periods of time and there is some evidence that the emergence of fleas is triggered by vibrations created by the host as it passes by. This seems to be the reason for the sudden appearance of numbers of fleas in homes that have not been occupied for some time.

Members
Fleas.

Food
Adults feed on blood while larvae feed on fragments of skin and other body debris.

Importance
Fleas are extremely important parasites of animals and humans. Apart from the irritation caused by bites, fleas are the vectors for a number of diseases such as murine typhus and plague. Allergic responses to flea bites are common as fleas inject saliva as an anticoagulant for continuous blood feeding.