1979] 
39 
O'Neill — Behavior of Philanthus psyche 
time. Males of the cicada-killer wasp, Sphecius speciosus establish 
territories near emergence holes and mate with newly emerged 
females (Lin 1963). However, there is evidence that in Philanthus 
spp. (including P. psyche) males do not establish territories until the 
females begin nesting; suggesting that mating does not occur at 
emergence but at some point during the nesting sequence. In P. 
psyche, P. bicinctus (Gwynne in preparation), P. zebratus (Evans 
and O’Neill 1978 and unpublished), P. triangulum (Simon-Thomas 
and Poorter 1972), P. multimaculatus (Alcock 1975a), and P. 
pulcher (personal observation) copulations were observed after 
females began nesting. 
Given that the general nesting area seems to be the location with 
the highest probability of encountering a female that becomes 
sexually receptive sometime during the nesting sequence, a male of 
P. psyche can identify this spot by simply establishing a territory 
where he first emerged since the previous year’s nesting area is likely 
to be this year’s. Even if successional changes result in females 
moving a short distance to a new nest area, the habitat type is such 
that males should be able to recognize it and move with them 
Therefore, following Alcock’s (1975a, see introduction) criteria, a 
territorial sphecid such as P. psyche is characterized by clumping of 
females and an apparent ability of males to locate areas where this 
occurs. 
The third of Alcock’s criteria is the defendability of the territory 
in terms of the male’s time and energy budget. One limitation on 
defendability is the amount of time spent on intraspecific male-male 
encounters, a function of the relative population density. If a male 
spends too much time on aggressive interactions with conspecific 
males, he wastes time and energy that could be used for scent 
marking and contacting females. Although these encounters are 
common, they by no means occupy the majority of the male’s time. 
In addition, the territories are nonresource-based (i.e., they contain 
no food, plants, or foraging sites and males do not control access to 
nesting sites). Thus, defendability is not limited by the need to 
include resources in the territory; which, if a minimum number were 
necessary, might result in territories too large to be defended and 
occupied exclusively. Several consistently occupied territories of 
this species contained only one plant. 
Evidence thus far collected substantiates the suggestion of Alcock 
(1975a) that abdomen dragging functions to deposit a pheromone. 
However, at this point in the research a description of the specific 
