Vi 



Vol. XXIX, pp. 173-204 September 22, 1916 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



DISTRICT OF COLUMBIA DIPTERA: SYRPHIDtE. 



BY NATHAN BANKS, C. T. GREENE, W. L. McATEE, AND 



R. C. SHANNON. 



INTRODUCTION. 



Because of the conspicuous coloration of many forms, their 

 frequency about flowers, the wonderful similarity of certain 

 species to wasps and bees, the remarkable larvae of Eristalis and 

 Microdon, the connection of one form with the Bugonia myth, 

 and the economic importance of various species, the Syrphidae 

 are considered one of the most interesting of the families of 

 Diptera. The excellent revision* of the family by Dr. S. W. 

 Williston has made them available for study to all who collect 

 flies ; it is therefore natural that the list of Washington Diptera 

 should begin with this family. 



The habits of the Syrphidae are of such a varied nature that 

 it is not possible to thoroughly investigate the Syrphid fauna of 

 a given locality in a few years. Certain species occur very 

 sparingly in the early spring, when little collecting is done, 

 while others occur only late in the fall. A number are very 

 local, and if the right spot is not examined at the right time 

 the species will not be found in years of collecting. Various 

 species appear to be really rare. A considerable number are 

 very expert on the wing, and the collector, by no means, cap- 

 tures all he sees. Moreover in recent years it has become 

 apparent that in several genera there are more species than have 

 been customarily recognized, some of which are not easily dis- 

 tinguished in the field. The area covered by the present list is 



* Bui. 31. U. S. Nat. Mus., 335 pp., 12 pis., 1886. 



34— Proc. Biol. Soc. Wash,. Vol. XXIX. 1916. (173) 



