Female macroptera. Body brown to light brown, legs yellow with light brown shadings; antennal segments I–III brownish yellow, IV–VIII brown; fore wings pale at base then brown but paler medially then again a little darker at apex. Antennae 8 (or 7) -segmented; VI usually with base of major sensorium exceptionally broad. Head slightly longer than wide; ocellar setae III arise just within or just outside triangle. Pronotum with transverse markings sometimes scarcely visible, discal setae varying in number from 10–24, external postero-angular setae scarcely 0.4 as long as inner pair. Metanotum longitudinally striate medially, median setae at anterior margin, campaniform sensilla absent. Fore wing first vein setal row complete with about 18 setae. Abdominal tergite II with 4 lateral margin setae; tergites with no sculpture medially; tergite VIII with ctenidia terminating anterior to setae S3, posteromarginal comb almost complete but irregular medially. Sternites and pleurotergites with no discal setae; sternite III usually with circular or transverse pore plate.
Male macroptera. Body yellow; sternites III–VII with small circular pore plate.
There are 33 species of Thrips genus known from Australia, out of a total of 280 species worldwide (Mound & Masumoto, 2005). Many of these species have the antennae clearly 7-segmented, whereas others have 8 segments. Some species have two complete rows of setae on the fore wing veins, whereas others have the setal row on the first vein more or less widely interrupted. Moreover, some species have sternal discal setae, whereas other species have only marginal setae on the sternites. Despite this variation, all members of Thrips genus have paired ctenidia on the tergites, and on tergite VIII these are postero-mesad to the spiracles, and they also lack ocellar setae pair I in front of the first ocellus. In contrast, Frankliniella species have ctenidia on tergite VIII antero-lateral to the spiracles, and a pair of setae is always present in front of the first ocellus. T. knoxi is particularly unusual within the genus Thrips in the enlarged base of the sensorium on antennal segment VI, and in the presence on sternite III of females of a small pore plate.
Known only from Australia.
Queensland, South Australia.
Feeding and breeding in flowers.
Various species of Lomandra (Xanthorroeaceae).
Thrips knoxi (Girault)
Mound LA & Masumoto M. 2005. The genus Thrips (Thysanoptera, Thripidae) in Australia, New Caledonia and New Zealand. Zootaxa 1020: 1-64. http://www.mapress.com/zootaxa/2005f/zt01020p064.pdf