Thysanoptera (Physapoda: Thrips)
Small or minute slender-bodied insects with short 6- to 10-segmented antennae and asymmetrical piercing mouthparts with maxillary and labial palps. Prothorax well developed, free; tarsi 1- or 2-segmented, each with a terminal protrusible vesicle. Wings wh
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THYSANOPTERA (PHYSAPODA: THRIPS) Small or minute slender-bodied insects with short 6- to 10-segmented antennae and asymmetrical piercing mouthparts with maxillary and labial palps. Prothorax well developed, free; tarsi 1- or 2-segmented, each with a terminal protrusible vesicle. Wings when present very narrow with greatly reduced venation and long marginal setae. Cerci absent. Metamorphosis accompanied by two or three inactive pupa-like instars.
These insects are commonly known as 'thrips'. The maJonty vary in length from o· s-8 mm, the smaller forms being by far the most prevalent. They are mostly yellow, yellowish-brown or black and many are found among all kinds of growing vegetation, both on the flowers and about the foliage; others are subcortical or frequent moist decaying plant remains, particularly wood, leaf litter and fungi. Some species are predacious, or at least occasionally so, and suck the body-fluids of aphids, mites and other small insects. When disturbed some species crawl in a leisurely fashion, others run quickly or leap, and a large number are able to fly but do not readily do so. Many exhibit the habit of curving the apex of the abdomen upwards and in winged individuals this movement is generally preparatory to flight; the insect uses its legs to comb the long setae on the wings then flexes the abdomen to separate the wings. For general accounts of the order see Priesner (1968) and the detailed review of its biology, ecology and economic importance by Lewis (1973). Most Thysanoptera feed by penetrating the living tissues of plants with their piercing mouthparts and imbibing the sap. It is therefore not surprising that they include a number of economically important species (Blunck, 1950; Bournier, 1970). Among the more widely distributed pests are Thrips tabaci on onions, Scirtothrips aurantii and S. citri on citrus in S. Africa and the United States respectively, species of Caliothrips and Frankliniella on cotton, Limothrips cerealium on cereals, and Heliothrips haemorrhoidalis as a pest of glasshouse crops in Britain. Most injurious Thysanoptera damage the leaves on which they feed, some affect the flowers or fruit and a smaller number induce the formation of galls. Thrips tabaci and species of
O. W. Richards et al., Imms’ General Textbook of Entomology © O. W. Richards and R. G. Davies 1977
THYSANOPTERA (PHYSAPODA: THRIPS)
Franklinie/la transmit spotted wilt virus, strains of which occur in tomato, tobacco, pineapples, lettuce and potatoes. On the other hand, several species play a role in the pollination of flowers, including those of crop plants, and one species, Liothrips urichi, was successfully introduced into Fiji to control the weed Clidemia hirta (Simmonds, 1933). Most winged Thysanoptera have a period of active dispersal by flight and in some abundant species such as Limothrips cerealium there are often mass flights, mainly associated with dry, sunny, settled weather (Lewis, 1964). Migration also occurs over longer distances through the agency of winds and of atmospheric conve
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