Scirtothrips citri Moulton, 1909

Biology
Breeding on a range of unrelated plants, but a major pest of Citrus in California.
Distribution
Southwestern U.S.A., but probably extending across southern States to Florida.
Recognition
Female macropterous; body colour yellow, antennal segments III – VIII grey; major setae pale; forewings pale. Antennae 8-segmented, III & IV with constricted apical neck, sense cone forked and stout. Head wider than long, postocular region and ocellar triangle with closely spaced transverse lines of sculpture; 3 pairs of ocellar setae present, pair III close together between anterior margins of hind ocelli; 2 pairs of major postocular setae present. Pronotum with closely spaced transverse lines of sculpture; posterior margin with 4 pairs of setae, B2 about 55 microns long. Mesonotum with pair of setae arising medially. Metanotum with irregular longitudinal reticulations on posterior half, campaniform sensilla absent, median setae close to anterior margin. Meso- and metafurca with spinula. Forewing first vein with 3 setae on distal half, second vein with 3 widely spaced setae; posterior fringe cilia wavy; clavus with 3 or 4 veinal setae. Tergites III – VI with median setae small but close together; II – VIII with lateral thirds covered in closely spaced rows of fine microtrichia, these microtrichial fields with 4 discal setae and posterior margin with fine comb; VIII with comb complete across posterior margin, lateral discal microtrichia extending across middle of tergite; IX with several rows of discal microtrichia. Sternites without discal setae, laterally with rows of microtrichia scarcely extending mesad of setae B1; posterior margins without comb of microtrichia; median setae on VII arising at margin. Male similar to female but smaller; tergite IX without a pair of stout curved processes (drepanae); hind femora without comb-like row of stout setae; sternites without glandular areas. Second instar larva white, antennal segments grey; tergites covered in irregularly arranged dot-like sculpture, pronotum without sculpture; setae capitate on head, posterior angles of pronotum, and tergite X, remaining setae small and acute; abdominal spiracles small.
Related species
This pale species has no microtrichia medially on the abdominal sternites, and the ocellar setae pair III arise behind the fore ocellus. Scirtothrips currently includes 90 species. Mound & Palmer (1981) gave a key to the major pest species, and Hoddle and Mound (2003) gave a key to the Australian species.

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