Mar., 1912.] 
Life-Histories of Syrphidae III. 
487 
Adult. 
Description after Wiedemann, Auss, Zw. Ins. II. 129, 22, and 
Osten Sacken, Proc. Bost. Soc. Xat. Hist. XVIII, 145. 
cf , $ . Length 8-10 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 antennae; 
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 yel- 
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 border; 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, forming a sharp angle anteriorly, and a 
rounded one posteriorly ; the former 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 tibiae 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 
