The Embioptera (Embiidina) comprise one of the smaller, lesser-known orders of insects.
Like their distant relatives, stick insects, termites and earwigs, embiids are essentially tropical, but some species occur in warm-temperate climates. The order is well represented throughout Australia, two species even occurring above 2000 metres in the Australian Alps. Less than 200 species are recorded for the world, but recent field work indicates that as many as 2000 may exist.
Because of almost complete confinement of activity to their silk galleries, embiids are seldom seen by the non-specialist, except for alate males attracted to light. They are small to medium-sized, narrow-bodied insects, easily recognised by the greatly swollen fore tarsi which are packed with silk glands.
They may be aberrant derivatives of the orthopteroid stem group, owing their persistence to the survival potential afforded by life in silk galleries.
The Australian fauna has been described by Tillyard (1923), Davis (1936--44, 1944a) and Ross (1963), while Barth (1954) has given an excellent account of silk production. Ross (1970) reviewed the biosystematics of the order.
Mandibulate exopterygote Neoptera, with apterous females and winged or apterous males; living in silken galleries; fore basitarsi globose.
Embioptera are best represented on the great continental land masses of the tropics. Perhaps because dispersal is slow and limited by aptery of females, the order is sporadically distributed and very poorly represented on islands. Even such insect-rich islands as New Guinea and the Philippines have only related species-complexes of a single genus (
Australia, however, though peripheral to embiid centres, has an interesting fauna developed from three basic stocks, which were undoubtedly gained by way of land connections with south-eastern Asia, while perhaps a species or two moved southward from New Guinea by way of a Torres Strait connection. Two species have recently been introduced in commerce.
Apparently, the order has not reached New Zealand, and it is absent from Chile and Patagonia. As may be expected in a tropically centred group, there is no evidence of faunal exchange through southern connections.