164 ERNEST A. BACK. 



gins of these segments. Pile of abdomen moderately abundant and 

 white. Legs clear yellow; often very much faded; hind femora in- 

 crassate and sometimes with a darker distal portion; hind tibia; fuscous 

 at tip. Empodia present. Wings hyaline, costa yellowish; second 

 posterior cell but little longer than the third; the fourth with a short 

 but variable peduncle. 



Type. — M. C. Z. flavipes and favillaceus . There are five 

 specimens of flavipes, one of which bears a label in Loew's 

 handwriting; favillaceus is represented by a single female 

 specimen. 



Habitat. — Atlantic States, not rare; Neb. (type) ; Bev- 

 erly (June 18; July 7 and 10), Amherst (June 14, 15, 23; 

 July 8, 15; Aug. 5) and Williamstown (June 27, Scudder), 

 Mass.; Mosholn (June 20) and Forest Park, L. I. (June 14), 

 N. Y.; Newark (June 16) and Dunnfield (July 15), N. J.; 

 Champaign Co., 111.; Mich.; Minn. 



I believe that flavillaceus is none other than a large flavipes. 

 Loew described favillaceus from a single female which shows 

 traces of indistinct yellowish bands on the same segments of 

 the abdomen that they appear on in flavipes. Loew had at 

 most but two specimens from which to make his description 

 of flavipes. I have studied about twenty specimens of flavipes, 

 and they show such a variation in size and distinctness of color- 

 ation that I believe that these two species should be united. 

 The type of favillaceus is somewhat larger than most spec- 

 imens of flavipes, but some of the latter are as large. 



Leptogaster hirtipes. 



Leptogaster hirtipes Coquillett, Pro. Ent. Soc. Wash., VI, 178, 

 1904. 

 rf 9- — Length 11-14 mm. — Hind femora whitish at base, yellowish- 

 brown on swollen portion, the proximal half of the latter beneath with 

 a conspicuous patch of snow-w^hite pile. Antennae yellowish, occiput 

 above with black bristles, abdomen not distinctly ringed, the second 

 posterior cell of the hyaline wings much longer than the third. 

 * Face silvery white pruinose with a rather dense pure white mystax; 

 the front and occiput more grayish pruinose. Bristles of the upper 

 occiput rather stout, black, the remaining bristles along the outer 

 orbits and the scant beard white; proboscis polished black. Antennae 

 yellowish, the third segment considerably shorter than the bristle-like 

 style, oval, tapering slightly at each end and often darker than the 

 basal segments. Thorax black, the humeri and posterior callosities 



