Mar., 1912.] Life-Histories of Syrphidae III. 487 



Adult. 



Description after Wiedemann, Auss, Zw. Ins. II, 129, 22, and 

 Osten Sacken, Proc. Bost. Soc. Nat. Hist. XVIII, Ho. 



cf , 9 . Length S-10 mm. Female. Face yellow, in certain 

 positions with a pearly luster, with a brown stripe in the middle, 

 which begins at the oral margin but does not reach the antenna; 

 the latter brownish-black, reddish on the underside of the third 

 joint. Cheeks blackish, but separated from the mouth by a narrow 

 yellow border, which on the underside of the mouth completely cuts 

 off connection between the black color on both sides. Front 

 brownish bronze color, powdered with yellow on each side. Im- 

 mediately above each antenna there is a brownish spot sometimes 

 continued above into an indefinite black stripe; vertex metallic 

 bronze or black, eyes bare. Thorax metallic greenish black, 

 unstriped; with scattered luteous pile; on the sides, in front of 

 the base of the wing, yellowish; elsewhere metallic green; scutel- 

 lum metallic yellow, with a bluish reflection and sparse 3^el- 

 low pile. First abdominal segment metallic blue; the rest of the 

 abdomen black with bright yellow cross-bands. The first abdom- 

 inal cross-band is not interrupted but co-arctate in the middle; 

 its ends do not touch the margin of the abdomen, but are separated 

 from it by a narrow black l3order; sometimes a brownish mark in 

 the middle of this band gives it the appearance of being sub- 

 interrupted. The second cross-band is nearly as broad as the 

 black cross-band between it and the next yellow band ; it is usually 

 perfectly straight (in some specimens the hind margin is gently 

 sinuate) ; its ends do not touch the lateral margin of the abdomen ; 

 they are cut obliquely, fonning a sharp angle anteriorly, and a 

 rounded one posteriorly ; the fornier almost touches the margin of 

 the abdomen. The third band is similar to the second, only its 

 hind margin is more perceptibly arcuated. The posterior margin 

 of the fourth segment has as usual, a narrow yellow border; the 

 fifth likewise, and two yellow spots at the base besides. Femora 

 yellow; the four anterior ones in some specimens brownish at the 

 extreme base only ; the hind pair with a more or less dictinct brown 

 ring on the distal half; four anterior tibia? and tarsi yellow; the 

 hind tibiae sometimes with a brownish ring, the hind tarsi brownish. 



Male (Fig. 44). Front yellow, with a more or less distinct 

 brown spot above each antenna; cross-bands on the abdomen 

 broader than in the female, and distintly broader than the black 

 interval between them; posteriorly, they are often nearly straight, 

 sometimes distinctly arcuate, especially the third band. The 

 yellow spots on the second segment are not coalescent, but sepa- 

 rated by a narrow black interval (in some specimens sub-coales- 

 cent) ; the fifth segment is yellow, with a black spot in the middle. 

 The four anterior femora are black at the base; the hind femora 



