1928] 
A Note on the Genus Pelecinus 
205 
A NOTE ON THE GENUS PELECINUS.* 
By Chyrles T. Bkues. 
The peculiar hymenopterous genus Pelecinus is represented 
in North America by P. polyturator Drury, which extends also 
into South America. Over the southern part of its range, this 
species varies greatly in color and a number of species have been 
described from tropical America which are perhaps only varia- 
tions not worthy of specific rank . 2 Pelecinus is highly dimorphic 
and the sexes can be instantly recognized by the form of the ab- 
domen. In the male, this part of the body is strongly clavate and 
less than twice as long as the remainder of the body, whereas in 
the female the abdomen is linear and fully five times as long as 
the head and thorax together. The female of this insect is a 
common North American insect, and has been bred from the 
larvae of scarabseid beetles of the genus Phyllophaga ( =Lachnos - 
ternd). The male on the other hand is very rarely seen and is 
always regarded by those familiar with the species as a very 
unusual find. Since the female is frequently seen in great num- 
bers, there can be no question that the male is actual^ very 
scarce and that practically all the individuals of the species in 
the United States are females. It would seem therefore that 
these females must ordinarily reproduce parthenogenetically and 
that under such circumstances female progeny are produced; i. e ., 
that they represent a thelytokous race. On the other hand, 
among the neotropical color varieties males are well represented 
in the population for they are frequently obtained by collectors. 
This makes it probable that the economy of the tropical forms 
is widely different from that of the nearctic ones. 
Ashmead 3 makes the statement that the female is not rare 
in some of our northern states during August and September 
Contribution from the Entomological Laboratory of the Bussey Institu- 
tion, Harvard University, No. 302. 
2 Cf. Roman, Ent. Tidskr., 1910, p. 196. I am inclined to believe, however, 
that there is more than one neotropical species since two males that I have 
seen show a great difference in the form of the first abdominal segment, 
exactly as figured by De Romand nearly a century ago. (Mag. Zool., 1842, 
pi. 86). 
3 Journ. New York Entom. Soc., vol. 10, p. 243, 1902. 
