Both sexes fully winged. Body and legs dark brown, tarsi and apex of fore tibiae paler; antennal segment III yellow in basal half but with apex shaded, IV variably light brown, V dark; major setae dark brown, tergite IX setae paler; fore wing deeply shaded at base, then pale, but weakly and uniformly shaded for distal two-thirds. Head longer than wide; maxillary stylets retracted to eyes and close together medially; post ocular setae bluntly pointed, shorter than dorsal eye length; mouth cone extending to fore coxae. Antennae 8-segmented; segment III with one sensorium, IV with three sensoria; VIII short and broad at base. Pronotum with five pairs of bluntly pointed major setae, anteromarginals and anteroangulars shorter than postocular setae; epimeral sutures complete; prosternal basantra not developed, ferna present, mesopresternum lateral triangles weakly joined medially. Fore tarsus without a tooth. Metanotum weakly reticulate medially, median setae acute. Fore wing parallel sided, with about 10 duplicated cilia; three softly pointed sub-basal setae sub-equal in length. Tergite IX setae S1 and S2 pointed, slightly shorter than tube.
Male similar to female; tergite IX setae S2 shorter; sternite VIII without a pore plate.
Several Liothrips species described from California cannot at present be recognized, and the identity of L. dumosus is unclear. Judging from the available specimens in the Ewart Collection, collected from Prunus demissa, it is variable in the color of the antennae and tarsi. It is similar to L. ilex in general appearance, but has the pronotal setae blunt rather than finely acute, and the fore wing less deeply shaded. Currently, there are 290 species listed in the genus Liothrips, although 30 of these are placed in two sub-genera known only from Asia. As a result, this is larger than either Thrips or Haplothrips, these three being the largest genera of Thysanoptera. However, in comparison to both Thrips and Haplothrips there are far greater problems in Liothrips in species recognition. A particularly high proportion of the described species are known from single samples, or even single individuals, resulting in little knowledge of variation within and between species, and thus the general assumption that most members of the genus are host-specific requires extensive testing. Stannard (1957) listed 32 species of Liothrips from North America, and subsequently (Stannard, 1968) included 14 of these in his keys to the Illinois fauna. Cott (1957) treated 11 species from California, two of which he placed in Rhynchothrips, but currently from this State there are 13 Liothrips species listed (Hoddle et al., 2004) of which several cannot at present be recognized.
Liothrips dumosus (Moulton)
Presumably breeding on leaves
Reported to be specific to Prunus ilicifolia (Rosaceae) (Cott, 1956).