28 B. C. ENTOMOLOGICAL SOCIETY 



KEY TO THE GENERA 

 Orothripinae Bagnall 

 a. Labial palpi S-segmented ; head wider than long. 



b. Terminal antennal segments more or less closely united. 



c. Antennae moderately slender, inserted very closely together, 

 segments 7-9 more or less compactly united ; maxillary palpi 

 clearly 8-segmented ; posterior margin of prothorax without 

 strong spine ; fore-tibiae unarmed ; fore-wings expanded 

 apically, where they are twice as broad as near l)ase. 



Stomatothrips Hood. 



cc. Antennal segments 5-9 closely united Desmothrips Hood. 



bb. All antennal segments freely movable. 



d. Maxillary palpi 5-segmented* ; posterior margin of pro- 

 thorax bordered with several quite strong spines on either 

 side ; all tibiae armed ; fore-wings broader in distal third, 



narrower near base Orothrips RIoulton. 



aa. Labial palpi 3 or 4-segmented, head longer than wide. 



e. Antennal segments 8 and 9 closely joined and together, 

 somewhat shorter than segment 7 ; maxillary palpi 

 8-segmented; fore-wings very slightly narrowed before 

 the middle Erythrothrips Moulton. 



Melanothripinae Bagnall 



a. Antennae strongly geniculate, with tip of second segment strongly 

 produced inwardly beyond insertion of third, all segments free; fore- 

 wing coloured uniformly pale brown Ankothrips Crawford. 



aa Melanothrips. 



Aeolothripinae Bagnall 

 a. Head small, broader than long, rounded uniformly anteriorly, dis- 

 tinctly retracted into prothorax, forming a compact elliptical mass 

 with prothorax ; fore-wings narrow with two developed longitudinal 



veins 1nit without cross veins Franklinothrips Back. 



aa. Head and prothorax separated ; wings with cross-wings. 



b. Antennal segments 3 and 4 elongated, the fourth being three times 

 as long as the succeeding segments combined. 



Mitrothrips Trybom. 



* Moulton (U.S.D.A. Tech. ser. No. 12, Pt. 3) in generic key of Orothrips gives 

 labial palpi "four-segmented," but in the description of the genus and in the 

 species kelloggii gives labial palpi "five-segmented." No specimen of kelloggii 

 has been available for study, but in a specimen of its variety yosemitii the lanial 

 palpi are apparently four-segmented, but by careful lighting adjustment a small 

 fifth segment appears to be present. 



With Erythrothrips (U.S.D.A. Tech. ser. No. 21) Moulton in generic descrip- 

 tion gives labial palpi with three segments, but in the description of the species 

 arizonae labial palpi four-segmented. 



