Original reference: Pergande T in Duffey JC (1891) Footnote to "Transformation of a carabid (Plochionus timidus), and observations on a coccinellid enemy of the red spider". Transactions of the Academy of Sciences of St Louis 5 (3–4): 533–542.
Colour largely yellow but thorax and abdominal tergites with grey markings laterally; antennal segments I–II yellow, III–VIII grey; fore wings largely pale with three small dark transverse bands, basally, medially and subapically. Head with three pairs of ocellar setae, pair III very long and arising on anterior margins of ocellar triangle. Antennae 8-segmented, III & IV with forked sense cones. Pronotum rectangular and with few transverse lines of sculpture; six pairs of very long setae. Meso & metathoracic spinula well developed. Metanotum weakly reticulated posteromedially; paired campaniform sensilla absent; two pairs of setae, median pair very long and arising at anterior margin. Tarsi 2-segmented. Fore wing with first and second row of setae interrupted. Abdominal tergites II–VII with a small and wide apart median pair setae; tergite VIII without posteromarginal comb of microtrichia or craspeda. Sternites with no discal setae and with three pairs of long posteromarginal setae, median pair on VII arising submarginally. Both sexes fully winged.
Male with transverse pore plates on abdominal sternites.
Intraspecific variation
The body colour is presumably variable, and pale forms collected in Brazil might represent an extreme gradient of S. sexmaculatus. According to Hoddle et al. (2008), these colour differences might be due to environmental conditions during larval development, including temperature and the type of prey consumed.
Genus and similar species information
This Old World genus comprises about 15 species, and its members can be easily recognized by the six pairs of unusually long pronotal setae. However, species identification in this group is more difficult and relies heavily on character states based on colour. In S. sexmaculatus the abdominal tergites II–IV are shaded medially but yellow laterally, and tergites V–VII are usually pale or with weak shading.
World distribution
Described from USA, this thrips has been recorded widely around the world. However, identification of this species is not secure and some of the records may not be correct.
