

DASYPOGONINAE 



ROBBER FLIES OF THE WORLD 



201 



bristles; apex without spine. All tibiae and tarsi are 

 slender, the tarsi elongate, the claws fine and sharp, the 

 pulvilli long and slender, the empodium short and 

 slender. 



Wings: The wings are immaculate; marginal cell 

 very widely open. The anterior branch of the third 

 vein ends at the wing apex. The fork of the third vein 

 is situated a little beyond the posterior crossvein. An- 

 terior crossvein rectangular, placed at outer fourth of 

 discal cell. Middle end vein of second basal cell is 

 long. All of the posterior cells and the anal cell wide- 

 ly open. 



Abdomen : The abdomen is moderately long, convex, 

 with only slightly tapered sides; at the base not quite 

 as wide as the mesonotum. Abdomen pollinose with 

 some bare spots, the pile fine, scanty and appressed, 

 except on the sides of the segments where there are 

 scattered, fine, erect, long hairs on the first four ter- 

 gites. First tergite with a few long bristly hairs. 

 Males with only seven tergites, this last being well de- 

 veloped. Females with eight tergites, the last two re- 

 duced, the eighth half as long as the seventh. Males 

 with the terminalia quite short and obtuse; as they 

 are more reduced ventrally they present a somewhat 

 oblique appearance in lateral aspect. The epandrium 

 is completely divided and separated, each lateral lobe 

 short ; proctiger small and short. The gonopod is well 

 developed but thrust obliquely upward from its lateral 

 portion. Hypandrium well developed, sloping up- 

 ward. Acanthophorites with 4 or 5 pairs of slender 

 spines. 



Distribution: Nearctic: Wilcoxia cinerea James 

 (1941). 



Genus Backomyia Wilcox and Martin 



Figures 145, 584, 972, 981 



Backomyia Wilcox and Martin, Journ. Kansas Ent. Soc, vol. 30, 

 p. 1, 1957. Type of genus: Eucyrtopogon limpidipennis 

 Wilcox, 1936, by original designation. 



Small flies of blackish color, related to Wilcoxia 

 James, Eucyrtopogon Curran, and Metapogon Coquil- 

 lett. At the apex the middle tibia bears a pair of 

 anterior, straight, spinous bristles, one of which is 

 usually black. The presence of long, slender bristles or 

 bristly hairs or both on the margin of the gently convex 

 scutellum separates these flies from Metapogon and 

 Wilcoxia. Length 5 to 8 mm. 



Head, lateral aspect: The face is only moderately 

 produced and is gently rounded over its whole extent, 

 retreating on its lower margin and with quite small, 

 nearly horizontal subepistoma. The occiput is promi- 

 nent in the middle and especially on the longer third 

 of the head, due to the strong, anteroventral recession 

 of the eye. It bears abundant, fine, long pile below with 

 a few weak bristles on the upper half. Proboscis short, 

 robust, not extended beyond the face with an anteriorly 

 directed circlet of apical hairs and a few fine, ventral 

 hairs below the base. Palpus of two segments, small, 



quite slender and cylindrical. The antenna is attached 

 at the middle of the head or slightly longer. The first 

 two segments are short and robust, the first segment 

 longer than the second and the first segment ventrally 

 with 2 to 4 stout, long, distinctly obtuse bristles; the 

 second segment has 1 or 2 similar bristles. Third seg- 

 ment more slender than the second, attenuate, li/ 2 times 

 as long as the first two segments combined, microseg- 

 ments excluded. The first microsegment is quite short, 

 distinct and the second is more than half the leno-th 

 of the third segment. 



Head, anterior aspect : The head is of medium width, 

 the face below the antenna is a little more than a fifth 

 the head width, rather strongly widened below. It 

 bears dense, loose micropubescence and numerous, long, 

 slender, bristly hairs which begin on the upper fa cell 

 distance from the antenna of approximately equal to 

 the width of the first segment. Front widened and the 

 vertex nearly as wide as the lower face. Surface of 

 front densely pollinose, the eye margins narrowly bor- 

 dered with quite long, stiff hairs. Vertex only mod- 

 erately excavated; the ocellarium is large, not high, 

 with vertical sides and between the posterior ocelli is a 

 pair of long, slender bristles, a pair behind, sometimes 

 weaker, and several pairs of long, bristly hairs on the 

 anterior portion of the ocellarium. 



Thorax: The thorax is comparatively short, with 

 moderately high mesonotum which is rather strongly 

 arched. It bears numerous, long, stiff or bristly hairs 

 undifferentiated and the lateral bristles are long and 

 comparatively slender. There are 2 or 3 notopleural 

 bristles, 1 supraalar, 1 or 2 on the postalar callosity, 

 and the scutellar margin has 3 pairs of bristles. Sur- 

 face of mesonotum and the slightly convex scutellum 

 pollinose. Humerus with bristly hairs, metanotum 

 laterally with pollen only. Pronotum and propleuron 

 with abundant, fine pile. Metapleuron with 4 long, 

 slender, anterodorsal bristles and behind with a row of 

 more numerous, slender, bristly hairs. The anterior 

 elements are sometimes black. Postmetacoxal area 

 membranous; lateral and ventral metasternum pilose; 

 presternum dissociated. 



Legs: The femora are stout without being swollen 

 and they bear abundant, long, fine pile with weak 

 bristles restricted to the apex. Hind femur with 3 

 lateral apical and 1 dorsolateral apical bristle and 1 or 2 

 weaker dorsomedial apical bristles. Only the dorsal 

 surface has short, appressed setae. Anterior and 

 middle femora similar, the apical bristles being much 

 weaker in character and on the anterior femur re- 

 stricted to the front. Hind tibia with 3 dorsolateral 

 and 2 distal dorsomedial bristles besides 3 ventrolateral 

 bristles on the outer half and also a ventral, medial 

 and anterior fringe of a few, long hairs restricted 

 chiefly to the basal half. These fringes of bristly hairs 

 become very prominent on the anterior and middle legs, 

 especially on the anterior and middle surfaces of the 

 posterior tibia ; its posterior surface bears 12 such hairs 

 in the male of Backomyia limpidipennis. In females 

 they are fewer in number and less conspicuous and they 



