188 BULLETIN 31, UNITED STATES NATIONAL MUSEUM. 



HelophiluB latiA'ons. 



Helophilm latifrons Loew, Centur.,iv, 73; Osten Sacken, West. Dipt., 337. 



Habitat. — Massachusetts, Connecticut, Western Kansas, Wyoming, 

 Washington Territory, Montana, Oregon, California!, Red River of the 

 North (O. S.) 



5,9. Length, 13 to 15"°". Face yellow, thickly covered with light 

 yellow polleu and pile, leaving in the middle a moderately broad, shin- 

 ing, red dish -yellow stripe, which ends acutely a little below the anten- 

 nae ; the lower end at the oral margin black. Cheek black, shining, 

 pollinose behind. In profile the face is moderately concave above, from 

 the tubercle to the oral margin nearly perpendicular and straight ; the 

 lower border of the cheeks forms with the plane of the occiput but lit- 

 tle more than a right angle. The front in the male is broad above, in 

 width fully equal to half the distance between the foremost ocellus and 

 the base of the antennae ; across the ocelli black, a little shining, with 

 black pile ; below the front ocellus the black color is concealed beneath 

 dense yellow pollen, and wholly yellow pile, a small triangle above 

 the base of the antennae shining, reddish or brownish yellow. Scutel- 

 lum wholly translucent yellow, on the outer part sparsely and shortly 

 black pilose, but chiefly yellow pilose. First abdominal segment gray- 

 ish pollinose, with a black spot near the outer part, and the sides yel- 

 low. In the male the remaining segments as follows: Second segment 

 with a broad light-yellow cross-band, interrupted in the middle, leaving 

 a broad flattened triangle in front, opaque black, connected by a median 

 stripe with a narrotv posterior shining black cross-band ; third segment 

 with a similar yellow band, more narrowly interrupted, touching the 

 front margin, rounded on the inner angles behind, and leaving a broader 

 posterior shining black baud ; the opaque black is confined to a semi- 

 circular or semioval spot in the middle in front, separated from a smaller 

 one behind by two intervening, oblique, yellowish pollinose, transverse, 

 nearly contiguous spots ; fourth segment narrowly yellow on the sides, 

 across the middle a grayish-yellowish pollinose cross band, convex in 

 the middle in front, broadly emarginate behind; the black shining; the 

 posterior margin yellowish ; hypopygium black, concealed beneath dense 

 yellowish pollen. In the female the shining black cross-bands on the 

 posterior part of the second and third segments is broader; the yellow 

 cross-band of the third segment is narrower and more broadly separ- 

 ated, connected in the middle or nearly so by yellowish pollen ; the 

 black spot in front is usually not oval, but forming a more or less elongate 

 band, attenuated on the sides, but not reaching the lateral margins ; 

 the next segment similar to that in the male, but the yellow pollinose 

 band narrower and more gently biconcave; fifth segment shining 

 black, with a yellowish pollinose cross-band ; the yellow on the sides 

 of the fourth segment in both sexes may encroach on the ground of the 

 cross-bands, and also similarly in the fifth segment in the female. Legs 

 yellow ; base of front and middle femora, distal end of the front tibisB 



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