#thysanoptera

Thrips are some of the smallest insects in the world, usually 1 mm (0.04 in) long or less, and their rod-like, feathery wings are unsuitable for conventional flight. Instead, they exploit an unusual mechanism called “clap and fling” to create lift using an unsteady circulation pattern with transient vortices near the wings. They are the only insects, and the only animals, to fly using this method.

Thrips are mainly known for the small portion of species that cause damage and spread diseases to commercial crops. However, many other species exist, including many important pollinators, species that feed upon and inadvertently redistribute fungal spores, and even some that are parasites or predators of pest mites, other thrip species, and Codling Moths (Cydia pomonella).

Some flower-feeding thrips pollinate the flowers they are feeding on, and some scientists suspect that they may have been among the first insects to evolve a pollinating relationship with their host plants. Amber fossils of Gymnopollisthrips from the Early Cretaceous show them to be coated in Cycadopites-like pollen. Some thrips were pollinators of the Ginkgoales as early as 110-105 Mya, in the Cretaceous.

Thrips setipennis is the only pollinator of several rainforest plants native to eastern Australia, including the Veiny Wilkiea (Wilkiea huegeliana), Brush Muttonwood (Myrsine howittiana), and Variable Muttonwood (Myrsine variabilis).

The genus Cycadothrips are specialist pollinators of cycads (Order Cycadales), which are normally wind pollinated, but some species of Macrozamia are able to attract thrips to male cones at some times and repel them so that they move to female cones. Thrips are likewise the primary pollinators of heathers in the family Ericaceae, and also play a significant role in the pollination of Pointleaf Manzanita (Arctostaphylos pungens).

Some species of thrips within the subfamily Phlaeothripinae that specialize on Acacia hosts produce silk with which they glue together phyllodes to form homes inside which their semi-social colonies live.

Many thrips form galls on plants when feeding or laying their eggs. Some of the gall-forming Phlaeothripidae, such as genera Kladothrips and Oncothrips, form eusocial groups similar to ant colonies, with reproductive queens and nonreproductive soldier castes, which live within the galls they create.

In Australia, aggregations of male Common Blossom Thrips (Frankliniella schultzei) have been observed attracting females, so it seems likely that it is the males that produce the pheromones.

Females in many species guard their eggs against cannibalism by other females as well as predators.

In the fungus-eating Tube-tailed Thrips (family Phlaeothripidae) (image 4), males compete to protect and mate with females, and then stand guard over their eggs. Males fight by flicking their rivals away with their abdomen, and may even kill with their foretarsal teeth. Small males may sneak in to mate while the larger males are busy fighting.

Thrips are haplodiploid with haploid males (from unfertilised eggs) and diploid females capable of parthenogenesis (reproducing without fertilisation), many species using arrhenotoky, and a few using thelytoky.