Both sexes wingless. Body and legs brownish yellow, mid and hind tibiae also apex of tube darker, antennal segments I–IV mainly yellow. Head much longer than wide, cheeks convex and constricted to basal reticulate neck; compound eyes narrowed and prolonged on ventral surface; maxillary stylets retracted to postocular setae, wide apart and V-shaped in head. Pronotum with 3–4 pairs of rather short major setae, midlaterals not developed; prosternal basantra and ferna well developed, mesoeusternal border narrow no wider than interantennal projection. Fore tarsus with tooth. Metanotum sharply elevated medially, with concentric reticulation. Abdominal tergite I (pelta) fully transverse, partially fused to tergite II laterally; tergite IX setae S1 acute, about as long as tube.
Male with fore tarsal tooth large, fore femora expanded and L-shaped; tergite IX setae S1 and S2 equal in size.
A total of 27 species are listed in the genus Compsothrips, mainly in tropical countries but with seven described from North America. Of these seven, C. hookeri is widespread across the southern States from Florida to California, two species are from Florida, and four species are from various Western States. These species differ in the color of the basal antennal segments, but given that they are all wingless ant-mimics there must be considerable scope for studies on their behavior, as well as their inter-population variation using molecular data. C. yosemitae has the basal four antennal segments mainly yellow, paler than in any other species, and the body color is also pale.
Compsothrips yosemitae (Moulton)
Ant mimic, living at ground level
Imbibing spores of unidentified fungi.