Both sexes fully winged. Body, legs and antennae brown, antennal segment III yellow in basal two-thirds; fore wing pale with posterior half dark including clavus but sub-basal area entirely pale. Antennae 9-segmented, VII–IX forming a unit with IX much shorter than VIII; sensoria on III–IV linear, on III about 0.3 as long as segment, on IV more than 0.5. Head and pronotum with no long setae. Fore tarsus with recurved hamus small. Metanotum with one pair of setae at anterior margin and one pair near posterior, sculpture weakly arcuate around anterior margin. Fore wing slender with apex rounded. Abdominal tergites IV–VI with faint transverse lines of sculpture medially; trichobothria on X very small. Sternites IV–VI each with two pairs of posteromarginal setae and 12 to 14 setae on discal area, chaetotaxy on VII similar with two pairs of supernumerary setae submarginally.
Male similar to female but abdomen more slender; tergite I with pair of short longitudinal ridges.
A total of 12 species is listed currently in the genus Erythrothrips, although two of these (E. bishoppi from Texas and E. fasciculatus from California) cannot at present be distinguished satisfactorily from E. arizonae and these are all likely to represent the same species. Of the remaining nine species, one is from California, one from Argentina, two from Brazil, three from Peru, and two from Mexico (although these last two are also likely to represent a single species) (Mound & Marullo, 1993).
Erythrothrips keeni Moulton
Presumably breeding in flowers.
Bailey (1957) states that this species is common in the flowers of Chrysothamnus (Asteraceae) in the arid mountainous areas of California .
Oregon, California, Colorado, Idaho, Nevada.