This small order of highly specialised insects includes about 2380 described species and subspecies (Lewis and Lewis 1985), 88 described and at least one undescribed species being known to occur in Australia. The Siphonaptera are the only holometabolous order in which all adults are fully wingless. Larvae are characteristic although usually very small and cryptic, and trunk setation plays an important role in delimiting subordinal taxa.
The adults are 1-10 mm long (males usually smaller than females), strongly sclerotised, and have long legs which enable them to leap characteristically. The body is covered with backwardly directed setae and spines, sometimes arranged in combs (
) facilitating progress through the hair or feathers of the host.
Fleas are so modified structurally for their particular kind of parasitic life (Snodgrass 1946) that their relationships with other orders are difficult to determine. They show equally striking biological adaptations, in that all stages, except perhaps the egg, can withstand unfavourable environmental conditions for remarkably long periods.
Their phylogeny, classification, host relations, physiology and medical and veterinary importance have been reviewed by Holland (1964) and Traub and Starcke (1980).
The interactive LUCID key available on this website (see the 'Identify Families' link) was written by Dena Paris from CSIRO Entomology.
Apterous, laterally compressed, endopterygote Neoptera, with piercing and sucking mouth-parts; ectoparasites of mammals and birds. Larvae apodous and vermiform, usually living in nests of hosts. Pupae adecticous, exarate.
Larval Siphonaptera are free-living scavengers, usually occurring within the nests, burrows or dwellings of their mammalian (or occasionally avian) hosts. Very few spend any significant length of time on the hosts themselves (although larvae of Uropsylla tasmanica appear to live permanently on dasyurids in southern Australia) (Dunnet & Mardon 1991).