174 Proceedivgs of the Biological Society of Washington. 



that ordinarily considered as belonging to the flora and fauna 

 of the District of Columbia, namely, all localities within al)out 

 a 15-mile radius from the Capitol. However, insect collecting 

 has not been done with equal thoroughness in all parts of this 

 region. The Potomac Valley and the Falls Church region have 

 been much more extensively collected than other parts of the 

 vicinity. It is, therefore, certain that this list is far short of 

 completeness. It compares favorably, however, with lists given 

 for entire States, and therefore is entirely adequate for indicat- 

 ing the character of the fauna of an area so limited as ours. 



Collecting Syrphidse in the vicinity of Washington dates back 

 many years; Baron C. R. von Osten Sacken collected here from 

 1856 to 1862, and perhaps occasionally later, and from this 

 material several species were described by Hermann Loew. 

 Their material is in the Museum of Comparative Zoology. Later 

 Mr. Theo. Pergande collected generally around here, largely in 

 the Potomac valley; he sent his Syrphidse to Dr. Williston and 

 the specimens are now in the National Museum. About 1890 

 Mr. C. H. Tyler Townsend collected near Washington and pub- 

 lished a list of 18 species of Syrphidse; his specimens are in the 

 University of Kansas collection. Later, the senior author began 

 collecting here and in succeeding years was joined by the others. 

 The material collected by Banks is in his private collection ; 

 that collected by Greene in the collection of Forest Insects, Bu- 

 reau of Entomology, and the records are made available through 

 the kindness of Dr. A. D. Hopkins. The specimens gathered 

 by McAtee, Dr. A. K. Fisher, Messrs. W. D. Appel, L. O. 

 Jackson, and a few others, are in the Biological Survey. Those 

 obtained by Shannon are in the National Museum, and here 

 also are specimens collected by various other entomologists dur- 

 ing the last 15 or 20 years. Among these may be mentioned 

 D. W. Coquillett, H. S. Barber, D. H. demons, J. C. Crawford, 

 F. Knab, J. R. Malloch, and W. V. Warner. Mr. F. R. Cole 

 has generously furnished us with the records of Syrphidse col- 

 lected by him, and Mr. W. R. Walton has kindly read the 

 manuscript and added notes on the basis of his collection. 



Every collector who examines his vicinity carefully, comes to 

 the conclusion that he is on the border of zoological regions ; for 

 he finds species he did not expect, whose previously known 

 distribution was wholly southern, northern, western or eastern. 



