DiSVPOGONINAE 



ROBBER FLIES OF THE WORLD 



237 



long, coarse hairs. Palpus large, elongate, clearly of 

 two segments ; the first segment is excavated, the second 

 tapered, microporate, with bristly hairs on all sides and 

 the apex and also below the first segment. The antenna 

 is attached a little above the middle of the head, the 

 first and second segments rather short, the first one 

 especially robust, both with numerous long, slender 

 bristles below, laterally, and with bristly pile above. 

 The second segment ventrally has 2 or 3 stout bristles. 

 The third segment is narrow at the base, strongly 

 widened or dilated at the outer third and from this 

 point rather abruptly narrowed to the apex. This seg- 

 ment bears 1 short, stout, rather small, apically trun- 

 cate microsegment, at its end an open pit with spines. 



Head, anterior aspect : The head is wide, the face un- 

 usually wide and nearly one-third the head width, 

 slightly divergent below. Face densely pubescent, ex- 

 cept on the sides opposite the subepistomal area. Pile 

 absent, but the greater medial part of the gibbous por- 

 tion is densely beset with long, stout, pale bristles. 

 Subepistomal area large, concave and oblique. The 

 front is a little wider than the upper face, slightly 

 convergent at the vertex, pollmose with along the eye 

 a submarginal row of pile which changes to bristles at 

 the vertex and an additional segregated patch of pile 

 and weak bristles in the middle of each half of the 

 front. Vertex but little excavated, the ocellarium large, 

 with slanting sides and bearing 2 pairs of stout bristles 

 between the ocelli and 3 pairs behind. Eye facets 

 only slightly enlarged. 



Thorax: The thorax is pollinose with reduced pile. 

 There is an acrostical row or double row of bristles and 

 scattered, scanty, coarse hair laterally. The dorso- 

 central bristles are characteristic and consist of very 

 strong bristles anteriorly as well as posteriorly; there 

 may be 10 or more in each row. Lateral bristles quite 

 prominent and stout and long, and with the following 

 complement : 3 or 4 humeral, 2 or 3 notopleural, 2 su- 

 praalar, 2 postalar and 3 to 5 pairs on the scutellum. 

 Scutellum rather thin, flat and pollinose; pubescent 

 only. Pleuron pollinose, a vertical row of weak bristles 

 and bristly pile on the metapleuron, weak bristles or 

 only bristly pile on the pronotum, both anteriorly and 

 laterally. Lateral propleuron with dense tufts of long 

 pile, including the cervical sclerite. Metanotum micro- 

 pubescent only. Prosternum dissociated; lateral and 

 ventral metasternum pilose; postmetacoxal area 

 membranous. 



Legs: The femora are stout without being swollen, 

 with fine, flat appressed, somewhat bristly pile and on 

 the ventral surface of the first four, usually a few fine, 

 moderately long hairs, still fewer on the hind pair. 

 Femoral bristles quite few. Hind femur with 2 or 3 

 laterally on the basal third, none at the apex. Middle 

 and anterior femora each with 1 bristle posteriorly 

 near the outer fourth. All tibia with fine, short, ap- 

 pressed, scanty pile and rather numerous, short but 

 quite stout bristles. Hind tibia with 6 dorsolateral, 

 4 dorsomedial, 4 ventrolateral and 2 ventromedial 

 bristles on the outer half. The apex has 8 bristles. 



Middle tibia with 6 anterodorsal, 4 posterodorsal, 6 

 posterior, 3 posteroventral, the latter longer. Anterior 

 tibia with 8 anterodorsal, 4 posterodorsal, 3 posterior, 

 and 2 long posteroventral bristles. Apex with a quite 

 short process and distinct sharp, twisted spine. Basi- 

 tarsus with a cluster of denticles. Claws slender, 

 sharp; the pul villi well developed, slender; the em- 

 podium flattened. 



"Wings: The wings are immaculate, the marginal 

 cell widely open ; fork of the third vein at or beyond 

 the posterior crossvein. Anterior crossvein enters 

 the discal cell a little beyond the middle. All poste- 

 rior cells open, the fourth a little narrowed. Anal 

 cell widely open, or narrowly closed. Alula large; 

 ambient vein complete. 



Abdomen: The abdomen is comparatively robust, 

 distinctly tapered and at base a little wider than the 

 mesonotum, or equally wide. The abdomen is polli- 

 nose with scanty reduced pile, more or less appressed, 

 short in character, a little longer on the sides of the 

 first three tergites. Tergite one laterally with 3 to 

 6 stout bristles. Males with seven tergites, the seventh 

 only half as long as the sixth. Females with eight 

 tergites, the last being prominent. Male terminalia 

 rotate one-fourth. Epandrium cleft to the base but 

 each half tightly apposed for at least half of its length. 

 The gonopod is comparatively large, as long as the 

 epandrium, and tending to meet below to partly enclose 

 the terminal cavity. Hypandrium large, subtriangular 

 and broad at the base. Females with 5 or 6 pairs of 

 prominent, stout, blunt spines on the acanthophorites. 



Distribution: Nearctic: Lestomym atripes Wilcox 

 (1937); fraudiger "Williston (1884); montis Cole 

 (1916) : redlandiae Cole (1916) ; sdbulonum Osten 

 Sacken (1877); strigipes Curran (1931); unicolor 

 Curran (1942). 



Genus Lastaurus Loew 



Figubes 159, 548, 1069, 1078, 1950, 2008 



Lastaurus Loew, Bemerkungen iiber die Familie Asiliden, p. 11, 



1851. Type of genus: Lastaurus anthracinus Loew, 1851, 



by original designation. 

 Morimna Walker, Insecta saundersiana, vol. 1, pt. 2, p. 104, 



1851. Type of genus: Morimna maUophoroides Walker, 



1851, by monotypy. 



These are large, robust flies with comparatively dense, 

 long pile: often black or dark in color with smoky 

 wings but not all species have this coloration. Some 

 species resemble Mallophora Macquart or Laphria Mei- 

 gen at first sight. Lastaurus is related to Diogmites 

 Loew but is much more robust, with short but dense 

 pile on the abdomen and lateral margins of the meso- 

 notum. The femora are stout but not at all thickened ; 

 the tibiae and tarsi are, however, distinctly and more 

 than usually robust. The third antennal segment is 

 never spindlelike or dilated as in Diogmites. The face 

 is nearly plane but more conspicuous below due to the 

 normal anterior recession of the eye : it is pollinose only 

 but has two or three transverse rows of long, stout, 



