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They are described as holometabolous (having a complete metamorphosis even
though the nymphs look like small wingless adults) insects with 2 or 3 inactive
pupa-like instars. Thrips are the only members of the 'Exopterygote' (insects
whose wings develop outside there body and thus have externally visible wing
buds in the late nymphal and pupal stages, in comparison with the 'Endopterygote'
insects whose wings develop inside their bodies and are thus not visible until
after metamorphosis) to have developed a true pupal stage. They have asymetrical
mouthparts, having only one (the left) mandible, short 6- to 10-segmented
antennae and no cerci. Their wings when present are nearly equal, very thin with
little venation and a lot of hairs making a fringe around the edge, these hairs
greatly increase the effective size of the wings. Fully winged, brachypterous
(with reduced wings) and apterous (wingless) forms may occurr in the same
species, the wingless forms tend to be more common towards Autumn. They have
piercing sucking mouthparts. |