38 
Psyche 
[March 
nest entrance. Why is there a greater probability for males of P. 
psyche of intercepting a receptive female in the general nesting area, 
rather than in one of the other four above mentioned locations? 
As far as the first three rendezvous places are concerned, they 
should be fairly localized in order for the chance of encountering a 
female to be sufficiently high relative to the nesting area. At 
Roggen, females of P. psyche prey upon a diverse array of small 
hymenopterans (at least nineteen species in eight families; Evans 
unpublished data). Such a great variety of prey, assuming they 
themselves have diverse feeding habits as a group, would not likely 
be found in one place. Therefore, it is likely that the female hunting 
area is not concentrated. There are also no obvious concentrated 
patches of flowers of the type that females are likely to feed upon 
(e.g., Eriogonum spp.). Therefore, since foraging and feeding sites 
are relatively diffuse, clumping of females in these sites is improb- 
. able. As an effect of the above, there would be no concentrated 
landmark flyways between the nesting area and the foraging and/ or 
feeding localities over which the females would be likely to pass. 
Males of P. zebratus, in the Jackson Hole, Wyoming aggregation of 
this species, intercept females in flyways above the nesting area 
(Evans and O’Neill 1978). 
Mating at the nesting entrance occurs in the sphecids Oxybelus 
subulatus (Peckham 1977) and Oxybelus sericeus (Bohart and 
Marsh 1977, Hook 1978). In these species the male is territorial at or 
nearby the nest entrance, mating with the female each time she 
returns with prey. Although he concentrates his activities on a single 
female, it is assured that ther eggs are fertilized by him. Males of P. 
psyche often attempt to mate with females working at the nest 
entrance but in all cases observed are unsuccessful, as the female 
wards off all efforts of the males or temporarily leaves the area. 
Without the prospect of multiple matings, it would not pay the male 
to >vait at the nest entrance for the female as the time and e.nergy 
could be better spent searching for other females. 
Are males territorial in the nesting area because nesting females 
are present or because virgin females emerge there? In species in 
which thefemales mate only once, a male would gain an advantage 
by locating females as close to the beginning of their receptive 
period as possible. Assuming this, it may actually be the female 
emergence area that the male is interested in as a territory location. 
Males that scent mark closest to the emergence points would most 
likely be successful if females mate upon emergence for the first 
