The Thysanoptera comprises a single order in which the members, ranging in body length from 0.5 to 15 mm, differ from all other insects in the form of the mouth parts and also of the tarsal arolium. The mouth parts are asymmetric, with only the left mandible functional in larvae and adults, the right being resorbed in the embryo. The two maxillary stylets are co-adapted to form a single tube through which salivary secretions are pumped out into a plant and partially digested cell contents are pumped back into the thrips foregut (Chisholm & Lewis, 1984; Heming, 1993). The feeding apparatus thus differs fundamentally from the feeding stylets of Hemiptera such as aphids and coccids.
The interactive LUCID key available on this website (see the 'Identify Families' link) was written by Laurance Mound from CSIRO Entomology.
Larval thrips retain tarsal claws, but these are replaced in adults by an inflatable arolium (Heming, 1971) that functions in a similar way to that of dipterous flies.
Fringed wings, from which the order derives its name, also occur on small insects in several other orders.
Modern evidence supports the view that thrips share a common, psocopteroid ancestor with the Hemiptera (Lyal 1985).
Worldwide, almost 6000 species of Thysanoptera are recognized currently, in nearly 800 genera (Mound 2008). Two sub-orders are recognized, the Terebrantia and the Tubulifera. Eight families are recognized in the Terebrantia, but only one family in the Tubulifera. Of the nine families, five are found in Australia. The Australian fauna is not well known.
Many aspects of structure, biology and phylogeny are reviewed by Mound, Heming and Palmer (1980). Lewis (1973) reviewed the ecological and economic information. Jacot-Guillarmod (1970-79) and Jacot-Guillarmod and Brothers (1986) catalogued many species.
Small, slender, dorsoventrally compressed, exopterygote Neoptera, with asymmetric piercing and sucking mouth-parts; tarsi with apical eversible bladders; wings, when present, narrow with reduced venation and fringe of long marginal setae or cilia; cerci absent. Metamorphosis intermediate between incomplete and complete, with two or three quiescent, pre-imaginal instars.
Mound and Houston (1987) list 422 species in 141 genera from Australia, but this is probably only about half the true fauna. The western and inland fauna is almost unknown. The richest fauna seems to be associated with the brigalow country of southern Qld. In the Phlaeothripidae, about 40 of the 89 genera and 240 of the 267 species listed are endemic to Australia; figures for the Aeolothripidae are 3 of 9 genera, and 21 of 24 species, and for the Thripidae about 5 of 42 genera and 65 of 128 species.
Many thripid genera have worldwide distributions, but the natural geographical extent of individual species is often difficult to determine as these insects are so readily distributed by winds and by trade (Mound 1983). The large number of introduced Thripidae probably also results from their small size, protected eggs and frequent polyphagy. A few Australian species have reached New Zealand (Mound and Walker 1982, 1986) and intrusions from the Oriental Region are probably increasing in northern Australia (Mound and Houston 1987).