GENUS LYPEROSIA 



373 



Stomoxydinae, especially those of Stomoxys and Stygeromyia, by 

 noting that the nude apical part of the arista is shorter than the last 

 bristle, whereas in Stomoxys the nude apical part is longer, or as long as 

 the last bristle ; the eyes are rounder and the wings straighter. The 

 posterior stigmata of the larva and pupa, as far as is known, are closer 

 together than is the case in the other Stomoxydinae ; the stigmal 

 slits are narrow and convoluted as in the larvae of the genus Musca. 



Lypcrosia is essentially an Old World genus, and the species have 

 probably been introduced into the New World by man. Bezzi has 

 published a valuable paper on the genus ; he gives the following key 

 to the identification of the better known species. 



BEZZI'S KEY TO THE SPECIES OF LYPEROSIA. 



Sixth longitudinal vein very long, always longer than the 

 distance between its extremity and the posterior margin ; 

 first longitudinal vein ending at the margin opposite the 

 inner cross-vein. First posterior cell narrow at its extre- 

 mity. Eight to ten aristal bristles close together. Hind 

 tarsi in the male serrated and dilated ; hind tibiae with a 

 long pre-apical bristle. Large-sized species (3 '5 to 5 mm.) . 



Sixth longitudinal vein short, shorter than its distance from 

 the posterior margin ; first longitudinal vein joining the 

 margin just before the small transverse vein. First poste- 

 rior cell not so narrow at its extremity. Six aristal bristles, 

 generally separated. Hind tarsi of male simple ; pre-apical 

 bristle of hind tibiae short. Small acrostichal bristles regu- 

 larly arranged in four longitudinal rows. Species of small 

 size (2 to 3'5 mm.) ........ 



Anterior acrostichal bristles longer, and irregularly arranged in 

 a row of six ; aristal bristles close together ; halteres yellow- 

 ish. Antennae, palps and legs nearly always dark brown to 

 black. Species larger ; Europe, Africa and America . 



Anterior acrostichal bristles short and regularly arranged in 

 longitudinal rows ; aristal bristles not so close together ; 

 halteres white. Antennae, palps, and legs often clear 

 yellow; sixth vein a little shorter. Small species (3'5 to 

 4 mm.) Central Asia and the neighbouring parts 



Body dark, markings on abdomen distinct. All macrochaetae 

 and bristles black except those of peristomum and pro- 

 pleural tuft, which are yellow. Frontal band black with 

 white pubescence ; proboscis glossy black, sometimes red- 

 dish. Antennae palps and legs black, cheeks and anterior 

 tibiae pale, sometimes basal segments of antennae are red- 

 dish. Wings light with black veins. Length 3'5 to 4'5 mm. 

 North and Central Europe and North America . 



irritans. 



exigua. 



irritans variety 

 typica. 



