262 
Psyche 
[Vol. 92 
unclear precisely what stimuli are critical in male territorial deci- 
sions. There are many lek territorial insects (Thornhill and Alcock 
1983), and perhaps these animals offer better opportunities to 
explore the proximate factors that underlie perch site selection in 
lek-forming species. 
Summary 
Males of the tarantula-hawk wasp Hemipepsis ustulata defend 
mating territories centered on individual plants of various species 
growing on ridges and peaktops in central Arizona. Males will leave 
their natural territories to investigate plastic and cardboard perch 
targets placed on top of aluminum poles, preferring higher to lower 
targets and large targets of high contrast to smaller targets of low 
contrast presented at the same height. A resident male will abandon 
his natural territory altogether in order to perch upon an artificial 
landmark, provided that the landmark is structurally complex and 
is taller than the shrub or tree that the male has been defending. 
Acknowledgments 
We thank Uta Matthes-Sears for her help in carting artificial 
perches through the desert. Jerry Waldvogel provided useful infor- 
mation on odor plumes on hilltops. This work was supported in part 
by National Science Foundation grant BNS 821 9791. 
References 
Alcock J. 
1979. The behavioural consequences of size variation among males of the 
territorial wasp Hemipepsis ustulata (Hymenoptera: Pompilidae). 
Behaviour 71:322-335. 
1981. Lek territoriality in a tarantula hawk wasp Hemipepsis ustulata 
(Hymenoptera: Pompilidae). Behav. Ecol. Sociobiol. 8:309-317. 
1983. Hilltopping territoriality by males of the great purple hairstreak Atlides 
halesus (Lepidoptera: Lycaenidae): convergent evolution with a pom- 
pilid wasp. Behav. Ecol. Sociobiol. 13:57-62. 
1984. Convergent evolution in perching and patrolling site preferences of 
some hilltopping insects of the Sonoran Desert. Southw. Nat. 29: 
475-480. 
Bradbury, J. W. 
1977. Lek mating behavior in the hammer-headed bat. Z. Tierpsychol. 45: 
225-255. 
