14 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63. 



former bearing a few indistinct hairs; usually the front and face 

 are of equal width but sometimes the face is slightly wider ; in pro- 

 file the front at base of antennae projects forward about one-fourth 

 to one-third of the eye width. Facial ridges bristly on the lowest 

 fifth; bucca one-twelfth the eye height; antennae black or yellow, 

 nearly as long as face, the third joint in both sexes three to four 

 and one-half times the second, arista thickened on the basal fifth 

 and in some specimens on the basal third, the penultimate joint 

 short. Thorax black, gray poUinose, with four black vittae; dor- 

 socentral macrochaetae variable, usually with four, sometimes with 

 three and occasionally with three on one side and four on the other ; 

 scutellum black at base, usually gray pollinose although quite often 

 3'ellowish, bearing three or four pairs of long marginal bristles 

 besides the apical pair which are directed backward and usually 

 cruciate; sternopleural bristles variable, usually two long and a ves- 

 tigial one, sometimes three and ver}^ often their development is so 

 variable as to exclude their use as a specific character; pteropleural 

 bristles about the size of the sternopleural ones. Abdomen variable, 

 may be either black, gray pollinose, or entirely yellow, excepting 

 a narrow black vitta on the dorsum, between these two extremes 

 there are many other shades. No discal macrochaetae present, first 

 and second segments bear one pair each of median marginal macro- 

 chaetae, third with a marginal row and the fourth wholly covered 

 with bristles two-thirds as long as the macrochaetae of the third 

 segment; abdominal hairs usually subdepressed, sometimes quite 

 erect, but if so they are short and inconspicuous. Legs brown or 

 black; usually the tibiae somewhat brownish; mid tibiae with one 

 bristle on the outer front side near the middle; hind tibiae short- 

 ciliate with one longer bristle near the middle, this longer bristle is 

 variable in length although always longer than the surrounding ones. 

 Third vein with two bristles at its base. 



Length 8 to 10 mm. 



Redescribed from many specimens from New England, Pennsyl- 

 vania, District of Columbia, Mississippi, Florida, Texas, and West- 

 ern United States and Canada. 



Type.—Q^X. No. 3596, U.S.N.M., from Mount Washington, New 

 Hampshire. 



Tlie species, as may be seen from the description, is very variable. 

 Many specimens of the various forms have been examined and we 

 are unable to find any good character to separate them. Certain 

 specimens from the Southern States are more yellowish and while 

 the black forms seem typical of the Northern States they are not 

 without exception. In the few specimens in which the genitalia 

 have been studied, we have found them quite alike in structure. 



