SYRPHIDAE OF MAINE. 255 



parts almost to the posterior respiratory '(process before which it 

 becomes a little elevated. The dorsal line begins with a very sharp, 

 nearly rectangular elevation in front, followed by a gentle flexure 

 reaching its greatest height a little in front of the middle. The descent 

 is gradual throughout the third quarter of the length, thence more 

 abruptly to the posterior respiratory organ. 



The pupal respiratory processes (Fig. 37-6A, 8) penetrate the pupa- 

 rium near the antero-dorsal flexure, about 2 mm. from the ventral line 

 and half a millimeter caudad. Each measures .35 to .5 mm. in length, 

 maximum diameter about .2 mm. Morel-shaped, the proximal half 

 being somewhat more slender, the distal half dilated and studded with 

 about seventy-five minute nodules. Each of these nodules when ver3 r 

 highly magnified (Fig. 37-7) is seen to consist of four, five or six oval 

 elevations each with a median slit. The anterior face of the expanded 

 part traversed by a branching shallow groove. The clumps of hooklets 

 on larval prolegs are conspicuous along the mid-ventral line and the 

 posterior respiratory process retains its larval characteristics. 



Adult (Fig. 37-10, 11). A small slender, nearly bare, fly, black with 

 yellow markings and very thick hind femora; marginal cell open, third 

 vein gently curved, anterior cross-vein near the middle of the discal cell. 

 Description adapted from Williston (62, p. 240) and Verrall (55, p. 612). 



Length, 7 to 8 mm. Face and front satiny yellowish white. Front of 

 female narrow above, shining black, with two small pollinose spots ; 

 vertical triangle of male elongate. Antennae reddish yellow. Dorsum 

 of thorax black, nearly bare, in front with two approximate pollinose 

 spots. The humeri and to the suture and all the pleurae yellowish or 

 whitish pollinose. Abdomen: opaque black in front, shining' behind ; 

 narrow sides of first segment and a broad spot at each side of the 

 second, yellow, somewhat whitish pollinose. "At the extreme produced 

 base of the second segment a remarkable fringe oi whitish hairs, 

 . the only obvious pubescence on the abdomen" (55, p. 613) ; 

 third abdominal segment with a smaller yellow spot at each basal corner 

 and the fourth with a narrow, interrupted yellowish-white pollinose 

 cross-band, the hind margin narrowly yellow. In the female the spots 

 smaller, the sides of the third segment in front metallic, scarcely at all 

 yellow, but with a light pollinose spot. Legs yellowish-red with obscure 

 brownish markings ; hind femora black, with the base and a usually 

 incomplete ring near the middle, reddish yellow ; hind tibiae at the 

 middle and tip brown or black. 



