Thrips are small hemimetabolic insects with a distinctive cigar-shaped bauplan: elongate with transversely constricted bodies. They range in size from 0.5 to 14 millimetres (0.020 to 0.55 in) in length for the larger predatory thrips, but most thrips are approximately a millimetre in length. Flight-capable thrips have two similar, strap-like, pairs of wings with a ciliated fringe, from which the order derives its name. Their legs usually end in two tarsal segments with a bladder-like structure known as an arolium at the pretarsus. This structure can be everted by means of hemolymph pressure, enabling the insect to walk on vertical surfaces (Heming 1971, Gillott 2005).
Thrips have asymmetrical mouthparts that are also unique to the group. Unlike the Hemiptera, the right mandible of thrips is reduced and vestigial - and in some species completely absent. The left mandible is larger, and forms a narrow stylet used to pierce the cell wall of tissues (Childers & Achor 1989). Some species may then inject digestive enzymes as the maxillary stylets and hypopharynx are inserted into the opening to drain cellular fluids (Hunter & Ullman 1989, Hunter et al. 1994). This process leaves a distinctive silvery or bronze scarring on the surface of the stems or leaves where the thrips feed (Heming Heming).
Thysanoptera is divided into two suborders: Terebrantia, and Tubulifera. These two suborders can be distinguished by morphological, behavioral, and developmental characteristics. Members of Tubulifera can be identified by their characteristic tube-shaped apical abdominal segment, egg-laying atop the surface of leaves, and three "pupal" stages. Females of the eight families of the Terebrantia all possess the eponymous saw-like ovipositor on the anteapical abdominal segment, lay eggs singly within plant tissue, and have two "pupal" stages.
- Childers, C. C., and D. S. Achor. 1989. Structure of the mouthparts of Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae). In B. L. Parker, M. Skinner and T. Lewis [eds.], Towards Understanding Thysanoptera. Proceedings of the International Conference on Thrips. USDA Technical Report NE-147, Radnor, PA.
- Gillott, Cedric (2005). Entomology. Springer. p. 234. ISBN 0-306-44967-6.
- Heming, B. S. 1993. Structure, function, ontogeny, and evolution of feedng in thrips (Thysanoptera). In C. W. Shaefer and R. A. B. Leschen [eds.], Functional Morphology of Insect Feeding. Entomological Society of America, Lanham, Maryland.
- Heming, BS (1971). Functional morphology of the thysanopteran pretarsus. Canadian Journal of Zoology. 49: 91–108.
- Hunter, W. B. & D. E. Ullman (1989). "Analysis of mouthpart movements during feeding of Frankliniella occidentalis (Pergande) and F. schultzei Trybom (Thysanoptera: Thripidae)". International Journal of Insect Morphology and Embryology 18: 161–171. doi:10.1016/0020-7322(89)90024-X.
- Hunter, W. B., D. E. Ullman & A. Moore (1994). "Electronic monitoring: characterizing the feeding behavior of western flower thrips (Thysanoptera: Thripidae)". in M. M. Ellsbury, E. A. Backus & D. L. Ullman. History, Development, and Application of AC Electronic Insect Feeding Monitors. Thomas Say Publications in Entomology. pp. 73–85.
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