DASTPOGONINAE 



ROBBER FLIES OF THE WORLD 



193 



tinued on to the top of the vertex ; sides of front with 

 stiff pile or bristles; the vertex is only moderately 

 excavated but the ocellarium is quite large and high, 

 with vertical sides, and bears usually 2 or 3 pairs of 

 very stout, long, divergent bristles and occasionally 

 additional hairs. In Heteropogon manicatus there 

 are several interesting differences; there is no pile on 

 the face ; bristles are restricted to the lower fourth ; the 

 front is only very slightly divergent, the vertex is con- 

 vergent, scarcely excavated at all, but the ocellarium is 

 moderately large and carries 3 pairs of stout bristles 

 arising on the posterior portion and curved forward. 

 Anterior eye facets strongly enlarged. 



Thorax: The mesonotum and pleuron are pollinose. 

 The pile is very fine and abundant and may be either 

 appressed or nearly erect. Bristles are prominent and 

 numerous. There may be a differentiated band of 

 acrostical pile separated by a bare space but this is less 

 evident in some species. Dorsocentral bristles may be 

 present and consist of 4 pairs before the suture or 3 to 

 5 pairs behind the suture, or they may be quite absent. 

 The lateral bristles are quite long and consist of 1 to 

 5 humeral, posthumeral bristles present or absent, 3 

 to 5 notopleural, 2 to 5 supraalar, 4 postalar, and 2 

 to 3 pairs of bristles on the scutellar margin, which 

 may be rarely absent. Margin of scutellum often with 

 considerable, quite fine pile, the scutellum is convex, 

 pollinose, with or without pile on the disc. The prono- 

 tum bears from G to 12 bristles, usually weak but some- 

 times stronger and characteristically with abundant, 

 long, quite fine pile, which becomes even more matted 

 and extensive below on the lateral propleuron and the 

 anterior coxa. The dorsal and posterior margins of 

 the mesopleuron and sometimes the posterodorsal corner 

 of the sternopleuron bear abundant, long, fine pile. 

 Metapleuron with a large, oval patch of exceptionally 

 long, coarse, pale pile and a similar smaller patch gen- 

 erally present on the hypopleuron. Metanotal callosity 

 micropubescent only. Lateral metasternum pilose, 

 postmetacoxal area membranous. 



Legs : The legs are stout without being swollen. The 

 hind femur is densely appressed setate, especially 

 above ; laterally the setae are sometimes more scattered 

 and there may be considerable rather long, fine pile 

 on the basal third both laterally and ventrally. The 

 bristles are stout but not numerous. Near the apex is a 

 medial and a dorsomedial bristle or sometimes only the 

 latter, and laterally are 2 similar bristles and some- 

 times an additional pair of dorsal, apical bristles, with 

 occasional subapical bristles as well. Exclusive of the 

 apex there are 2 or 3 lateral bristles but none ventrally. 

 The tibia has conspicuous bristles which consist of 5 

 or 6 dorsolateral, 4 or 5 dorsomedial, and 4 or 5 ventro- 

 lateral, the latter group sometimes restricted to the 

 outer half. The apex with 2 lateral, 2 dorsal, 2 medial, 

 and 6 ventral bristles. The tarsi are rather stout with 

 the second to fifth segments beadlike. Middle femur 

 with coarse, appressed, bristly pile and 5 anterodorsal 

 bristles on the outer half, or sometimes only 2 bristles, 

 and with 2 or 3 distal posterodorsal bristles. The 



middle tibia has conspicuous bristles consisting of 7 

 or 8 anterodorsal elements, the distal ones usually 

 longer ; it has also a few quite short porterodorsal and 8 

 to 10 longer posterior bristles, besides 4 or 5 quite long, 

 ventral bristles. 



Anterior femur and tibia quite similar to the middle 

 pair. Anterior tibia with 6 or 7 short, sharp, antero- 

 dorsal and 4 similar posterodorsal bristles, and 7 or 

 8 posterolateral and 3 or 4 ventral bristles, these latter 

 groups longer and usually of a different color. Sub- 

 apex with a circlet of 7 or 8 bristles and no spine or 

 protuberance. The tarsus, however, is a little more 

 slender, especially on the basitarsus which is longer 

 than the middle basitarsus. All 4 of the front tarsi 

 bear subapically a circlet of stout, long bristles con- 

 sisting of at least 2 anteriorly, 2 posteriorly, 2 dor- 

 sally, and 2 shorter ventral bristles. Claws slender, 

 sharp, curved chiefly at the apex. Pulvilli well devel- 

 oped ; empodium strongly swollen at the base and only 

 half as long as the claw. In some species the middle 

 tibia bears just beyond the middle a curious, dense, 

 flattened brush of coarse, black and white pile. Also in 

 some other species there tends to be at the apex of 

 the anterior and middle femur a flangelike extension, 

 especially on the anterior side, covered with a peculiar 

 type of appressed pile. 



Wings : The wings are hyaline or in part smoky, es- 

 pecially distally, or with the crossveins and the furca- 

 tion of the third and fourth veins with diffuse, clouded 

 spots. Marginal cell widely open, the second submar- 

 ginal cell at base is expended almost entirely anteriorly 

 and with little or no expansion behind the third vein. 

 The anterior branch ends a little before the wing apex, 

 the posterior branch ends nearly twice as far behind. 

 First posterior cell open in maximal width. Second 

 posterior cell often a little expanded, especially an- 

 teriorly. Upper section of anterior intercalary vein of 

 varying length, always well developed and always 

 much shorter than the rather strongly recurrent medial 

 crossvein, which tends to parallel or nearly parallel the 

 wing margin. Fourth posterior cell open but some- 

 times narrowed. Posterior crossvein present but short 

 or almost wanting. Anal cell narrowly open. The an- 

 terior crossvein is nearly rectangular and enters the 

 discal cell at the outer third or sometimes at the outer 

 two-fifths. Ambient vein complete; alula well devel- 

 oped; villi present or greatly restricted. 



Abdomen: The abdomen is robust, especially at the 

 base, which is wider than the mesonotum and gradually 

 tapering to the blunt, obtuse apex. The pile is rather 

 abundant, except on the last three female segments and 

 is fine, appressed, and setate or in part not setate. The 

 lateral margins of the first three segments often have 

 rather long tufts of very delicate pile which may be 

 matted and appressed, or quite erect, and which may 

 have also associated with it in some species coarse, 

 shorter, bristly pile. The first segment is comparatively 

 long and has 4 to 6 pairs of stout bristles with or with- 

 out longer pile. First 4 stern ites, and sometimes all the 

 sternites, with copious, conspicuous, long, fine, pale 



