Banks, Greene, McAtee, and Shannon — Dist. of Col. Diptera. 185 



S. KEENiANA Williston.— Dead Run, Ya., May 5, 1915, May 9, 1916, 

 Shannon; June 23, Banks. Five other specimens wliich may be only 

 very dark forms of keeniana were taken at Cabin John Bridge, Md., 

 April 28, 1912, F. Knab and J. R. Malloch; Plummers Id., Md., May 10, 

 1914, Shannon; Virginia near Plummers Id., May 2, 1909, McAtee; and 

 Dead Run, Va. , June 19 and 22, 1915, Shannon. 



S. LOBATA Loew. — Plummers Id., Md., May 18, 1915, Shannon; Mary- 

 land near Plummers Id., April 24, 1916, May 8, 1915, J. C. Crawford; 

 May 28, 1916, H. L. Viereck; Great Falls, Va., April 28, 1915, Greene; 

 April 20, 1916, McAtee; Chain Bridge, Va., June 4, Falls Church, Va., 

 June 26, Banks; Virginia near Plummers Id., Md., Juue 2, 1916, McAtee; 

 June 4, 1916, J. C. Crawford ; Dead Run, Va., May 11, 19, and June 20, 

 1916, Shannon. 



S. RUFiVENTRis Loew. — Plummers Id., Md., May 10, 1916, McAtee; 

 June 19, 1913, Shannon; Maryland near Plummers Id., May 8, 1915, on 

 Washingtonia, J. C. Crawford; May 10, 1916, McAtee; Dead Run, Va. , 

 May 11, 1916, Shannon; Virginia near Plummers Id., June 2, 1916, Mc- 

 Atee; June 4, 1916, H. L. Viereck and J. C. Crawford; Falls Church, 

 Va., June 6; Chain Bridge, Va., June 9; Great Falls, Va., May 25, 

 Banks. Immature specimens of this species are pale yellow. Sphegina 

 occur on flowers especially on those of Aruncus. 



Neoascia Williston. 



N. DisTiNCTA Williston. — Rosslyn, Va., May 1, 1913, Shannon; Falls 

 Church, Va., April 26, resting on a flower a few inches from the ground ; 

 June 4, 1916, Banks. 



N. GLOBOSA Walker. — Washington, D. C, July 14, A. N. Caudell; 

 Falls Church, Va., October 3, May 17, July 4; Great Falls, Va., June 21; 

 Dyke, Va. , May 14, Glencarlyn, Va. , May 30, 1916, Banks; seen hover- 

 ing around herbage about a foot from ground. 



Rhingia Scopoli. 



R. NASiCA Say. — Common; April 27 to October 21, in damp places, 

 often in partial shade, and at flowers of Impatiens, Viola, Nepeta 

 glechoma, and Hydrophyllum. 



Brachyopa Meigen. 



B. FLAVESCKNs Shannon.* — Dead Run, Va., April 9 and 24, 1916, May 

 23, 1915 ; June 9, 1915, May 19, 1916, Shannon ; hovering near chestnut 

 log on rocky hillside with northern exposure; originally described from 

 the locality cited. 



B. VACUA Osten Sacken. — Maryland near Plummers Id., April 28, 1914, 

 on blossoms of wild cherry, wild pear, etc., Shannon; Virginia near 

 Plummers Id., April 25, 1909, McAtee; Dead Run, Va., April 24, 1916, 

 *For description of female of this species see Appendix, p. 202, 



