THE GENITALIA OF MALE SYRPHID: THEIR MOR- 
PHOLOGY, WITH ESPECIAL REFERENCE TO 
ITS TAXONOMIC SIGNIFICANCE.*} 
C. L. METCALF, 
Ohio State University. 
The Syrphide are a group of very handsome flies, variously 
known as hover flies, flower flies and sweat bees; and, indeed, 
most often passed by the layman as stinging wasps or bees. 
There are perhaps 500 known species from North America 
and the individuals are very numerous so that it has been an 
attractive field for the systematist and there are many students 
of the group. A very excellent monograph of the family by 
Dr. S. W. Williston”, written in 1886, has also been influential 
in attracting attention to this family. 
Unhappily the impression has prevailed that these flies are 
easily classified; and many amateurs who would not have ven- 
tured to name a bug or a beetle or a mosquito, have created 
synonyms in this group after the most meager study. 
Nor has the confusion been confined to the collections of 
amateurs. I was surprised to find in the collections of four of 
the best known specialists of this group in America, four dis- 
tinct species under the name Sphegina lobata, and four different 
species named Spherophoria cylindrica. On the other hand in 
a number of cases the members of a single species were passing 
under two or three different names in these collections; e. g., 
Pipiza femoralis. 
This is not a reflection upon the systematists, but it is a 
good indication that the characters we have been using for this 
family (so largely color markings) are insufficient or untrust- 
worthy and misleading in many cases. The conviction seems to 
be general that the more trustworthy, taxonomic characters are 
the structural ones of shape or architecture, sculpturing or 
puncturation, and variations in the number, position, structure 
and proportions of the appendages. 
*An extract from a dissertation submitted to the faculty of the Bussey Institu- 
tion of Harvard University in partial fulfillment of the requirements for the degree 
of Doctor of Science, June, 1919. 
tContribution from the Entomological Laboratory of the Bussey Institution, 
Harvard University No. 190; and from the Department of Zoology and Ento- 
mology, Ohio State University, No. 67 
169 
