1916] Johnson — Some Neic England Syrphidw 75 



SOME NEW ENGLAND SYRPHID.E. 



By Charles W. Johnson, 

 Boston Society of Natural History. 



Microdon tristis Loew. 



The A'ariations of this species are not clearly defined and it is 

 difficult to separate them with the descriptions available. With a 

 series of thirty-seven specimens before me they seem to be readily 

 separated into two species by the form of the scutellum. In M. 

 tristis the scutellum is rather plane or flattened and somewhat 

 rugose, angulate and emarginate, with the spines at the extreme 

 angles, the pile thin so that the outline of the scutellum can be 

 seen distinctly. 



The other form has the scutellum noticeably convex, the margin 

 rounded and scarcely angulate, the small spines more approximate 

 and hidden in the long dense pile. The tarsal joints are slightly 

 more dilated and the abdomen of the females are as a rule much 

 broader. For this species the name M. cothurnatus Bigot can be 

 used, as I see no character to separate the eastern and western forms. 

 Bigot's type was from Washington and specimens from Seattle 

 agree with his description. It is more northern in its distribution 

 than M. tristis although both are found in southern New England, 

 northern New Jersey and Pennsylvania. Specimens before me 

 show the following distribution: Capens, Moosehead Lake, Ale., 

 July 15; Bretton Woods, June 24, and Halfway House, Mt. Wash- 

 ington, N. H., July 6 (C. W. Johnson); Kearsarge, N. H., July 2, 

 and West Chop, Mass., July 4 (A. P. Morse); Newton, Mass., 

 bred from pupse (F. C. Bowditch); Framingham, Mass., pupa, 

 April 19, imago. May 12 (C. A. Frost); Lyme, Conn., pupa, April 

 30, imago, May 26 (A. B. Champlain); Darien, Conn., (cf, 9) 

 June 12; Newark, N. J., June 14 (C. W. J.) and Lehigh Gap, June 

 28 (C. T. Greene). 



M. tristis was described from Virginia. I have specimens from 

 Pennsylvania, New Jersey, Connecticut, and as far north as Great 

 Barrington and Auburndale, Mass. 



