532 
Psyche 
[September-December 
Discussion 
To the best of our knowledge C. simplex provides the only docu- 
mented example of a wasp species whose males occupy fairly exten- 
sive home ranges in areas away from an aggregation of nesting 
females. Doubtless this only reflects the lack of research of male 
wasps and it is probable that home ranges embracing patches of 
flowers are a common phenomenon in male sphecids. 
The spacing system of male C. simplex does, however, differ from 
that of various close relatives, among them several species of Eucer- 
ceris as well as Philanthus and Clypeadon (Alcock, 1975 and in 
prep.). Males of these related species form relatively dense aggrega- 
tions with each individual applying an attractant pheromone from 
abdominal glands to a perch and vigorously repelling all intruders 
from an area roughly J 4 -I m in radius around the perch. Whether 
all the members of one genus share the same basic mating strategy is 
unknown and will require much further study, although the very 
limited current information hints that this may be the case (Alcock, 
in prep.) . 
Despite the differences between C. simplex and other philanthinine 
wasps there are some similarities as well. In all cases males occupy a 
perch to which they return after bouts of flying around. All pursue 
a remarkably wide range of flying insects evidently in an effort to 
determine the species and sex of the passerby or intruder. The key 
variable between different species is the area inspected by an indi- 
vidual. Those males that use a perch as a calling post defend it and 
a small area around it while C. simplex , which does not appear to 
employ an attractant pheromone, covers a much larger area (up to 
at least 40 m 2 ), so large as to be essentially indefensible. Attempts 
to drive all other males from a strip of roadside ditch 15 m X 2 m 
would require an extraordinary investment in aggressive territorial 
patrolling. Instead, C.' simplex males make no special effort to locate 
and repel conspecific males. Time and energy are devoted to re- 
peated investigation of a large area in a location likely to attract 
females, one which is rich in nectar-producing flowers or beetle- 
producing bushes. Having found a potentially good area, males re- 
main there becoming familiar with its prime spots. Presumably this 
is a superior strategy than one that would take a male on a random 
journey through the countryside in search of a mate. Because natu- 
rally occurring attractants (e.g. flowers) that draw in females tend 
to be patchily distributed, one would predict that males of other 
species that use such attractants to focus their search for females will 
