Syrphidae of Nebraska 51 



Seventy s S and eig-hty-four ? $ taken at Rulo, Richard- 

 son County; Omaha, Douglas County; Child's Point, Sarpy 

 County; Louisville, Cass County; South Bend, Cass County; 

 Beatrice, Gage County; Lincoln, Lancaster County; Cedar 

 Bluffs, Saunders County; Fairmont, Fillmore County; Con- 

 cord, Dixon County ; Curtis, Frontier County ; Mitchell, Scotts- 

 bluff County; Glen, Sioux County; Harrison, Sioux County, 

 and Monroe Canyon, between April 25th and September 27th. 



Tropidia Meigen 

 KEY TO THE SPECIES 



1. Femora black, at the tip testaceous; the hind femora below, near 

 the base, with a strong mammiform process {$) mammillata 



Front and middle femora yellow on distal end; hind femora 

 without such process near the base quadrata 



Tropidia mammillata Loew. Cent., i, 68 (1861); Williston, Synop. 

 N. A. Syrph., 208 (1886) ; Hunter, Canad. Ent., xxix, 144 (1897). 



Three S $ and one $ taken at Cedar Bluffs, Saunders 

 County, in April. 



Tropidia quadrata (Say). Amer. Ent., 1, (1824); Williston, Synop. 

 N. A. Syrph., 207 (1886). 



Twenty-five $ $ and seven ? $ taken at Lincoln, Lan- 

 caster County; Hickman, Lancaster County; West Point, 

 Cuming County, and Mitchell, Scottsbluff County, between 

 May 1st and September 16th. 



Pterallastes Loew 



Pterallastes thoracicus Loew. Cent., iv, 80 (1863); Williston, Synop. 

 N. A. Syrph., 198 (1886). 



Two $ $ taken at Omaha, Douglas County, July 22, 1913 

 (L. T. Williams) and Fairmont, Fillmore County, June 16, 

 1915 (C. E. Mickel). 



157 



