48 
Psyche 
[March 
lus that keeps the spiders together, since Dijkstra (1975) found that 
both male and female P. amentata prefer areas where draglines of 
both sexes have been laid. This preference for areas having silk of 
both sexes present may explain why females remain in the aggre- 
gation. Males remain in such areas due to a sex pheromone(s) 
presumably contained in (on) the female’s silk (Kaston, 1936; 
Hedge kar and Dondale, 1969; Richter, Stolting, and Vlijm, 1971). 
Furthermore, frequent displays and interactions by males would 
contribute to reduce locomotion into surrounding areas. On one 
hand, S. crassipes are attracted to one another and frequently in- 
teract, encountering an average of four conspecifics per minute. 
On the other hand, displays occurring during male-male agonistic 
interactions may serve to space individuals so that no spider in- 
trudes on the personal space of another (Aspey, 1976b). 
The edge effect in S', crassipes appears influenced by complex 
interactions among ecological and behavioral variables. Although 
food availability and environmental conditions may initially attract 
spiders to an edge habitat, predictions concerning the location of 
large spider populations within the habitat seem more influenced 
by microclimatic variables. Furthermore, social attraction among 
conspecifics maintain an aggregation within the restricted region. 
Thus, a delicate balance of social attraction modulated by definite 
inter-individual spacing interacts with ecological variables to pro- 
duce the phonomenon of the edge effect in S. crassipes. 
Acknowledgments 
I gratefully acknowledge Dr. Jerome S. Rovner, Department of 
Zoology and Microbiology, Ohio University, for his helpful guid- 
ance and encouragement throughout this research, and for his 
useful discussions of the material. Drs. S. W. F. van der Ploeg 
and H. Dijkstra, Free University, Amsterdam, The Netherlands, 
kindly offered helpful discussions and commented on the material. 
Literature Cited 
Almquist, S. 
1973. Habitat selection by spiders on coastal sand dunes in Scania, Sweden. 
Entomol. Scand. 4 : 134-154. 
Aspey, W. P. 
1974. Wolf spider sociobiology: An ethological and informational theory 
analysis of agonistic behavior in Schizocosa crassipes. Doctoral Dis- 
sertation, Ohio University, Athens, Ohio 45701. 
