|Unique features of thrips|
|In addition to their remarkably asymmetric mouthparts, in which the right mandible is not developed beyond a small basal sclerite in larvae or adults, thrips also exhibit several other unique features. The ordinal name “Thysanoptera” is derived from Greek words meaning “fringed wings”, and refers to the curious narrow wings of adult thrips. However, slender wings with long marginal fringing cilia occur on many other small insects, and adults of many thrips species are wingless.|
occidentalis - wing structures: a) bristles with special sockets
that retain them in different positions at rest and in flight; b) pterothorax
with base of fore and hind wing; c) abdomen with wing retaining setae
and ctenidia (photos: G. Moritz)
German the common name, “Blassenfüße”, refers
to the feet of thrips that lack typical insectan tarsal claws but bear
an eversible adhesive bladder or arolium. The English common name, “thrips”,
is derived from a Greek word meaning “wood worm”, and refers
to the fact that many non-pest thrips species are associated with fungi
on dead wood.
The life history of thrips species is also unique amongst insects. After the egg hatches, there are two larval stages, and both of these larvae move around and feed actively. However, these are followed by two separate, non-feeding, pupal stages (three pupal stages occur in all Phlaeothripidae), in contrast to the single pupal stage of most insect species. The eggs of thrips are commonly inserted into plant tissues, one at a time, using the saw-like ovipositor of females, but in all Phlaeothripidae the eggs are deposited on the surface of their food, whether plants or fungi.
|Frankliniella occidentalis - a) ontogenesis: egg stage, two larval stages, two separate, non-feeding, pupal stages, adult stage, b) tip of tarsus with arolium (foot bladder): left extruded and right retracted (photos: G. Moritz).|
|Frankliniella occidentalis - a) valvulae of the ovipositor with rows of sensillae to detect the depth of penetration during oviposition, b) section of a leaf of Saintpaulia with an empty egg shell shortly after hatching, c) leaf surface with a glued egg chamber, beneath: typical egg of an tubuliferan species with micropyles and hexagonal sculptered shell, d) Frankliniella fusca: brachypterous fore and hind wing (photos: G. Moritz).|
|Frankliniella occidentalis - a) successive steps of katatrepsis, b) Hercinothrips femoralis - embryo shortly before katatrepsis and during primary dorsal closure, c) Aptinothrips rufus: apterous female with typical fused pterothoracic region, d) Frankliniella fusca: brachypterous female with reduced fore and hind wing (photos: G. Moritz).|