50 
Psyche 
[March 
ceal the orb weaver and when the spider web flexes the stabilimentum 
may become a threat stimulus. A. aurantia construct more extensive 
stabilimenta than A. trifasciata. 
Web flexing, stilting and web flexing followed by stilting pre- 
dominate as responses to ventral presentations of a simulated preda- 
tor. Switching sides of the web, web flexing, switching sides followed 
by web flexing and moving away from the hub are main responses to 
dorsal presentations. Predator avoidance components are used dif- 
ferentially by the two species for both dorsal and ventral model pres- 
entations, by each species for dorsal vs. ventral model presentations 
and by various instars of one species, A. trifasciata. Juvenile re- 
sponses contain more components than adult responses and adult 
female A. trifasciata are more prone to rebuff or ignore the model 
than juveniles. Response thresholds differ significantly only with 
dorsal vs. ventral presentations of a simulated predator for both 
species. No significant differences in response thresholds exist between 
species and among instars of a species. Neither species becomes 
habituated or more sensitive to repeated model presentations. Web 
flexing response duration is not significantly different for either spe- 
cies when the simulated predator is presented dorsally vs. ventrally. 
Behavioral components and web architecture are believed to work 
together in the defensive strategies of these two orb weaving species. 
References 
Bristowe, W. S. 
1941. The comity of spiders, Vol. II. Johnson Reprint Corp., New York. 
Comstock, J. H. 
1940. The spider book. Rev. edit. Comstock Publishing Co., Inc., 
Ithaca, New York. 
Conover, W. J. 
1971. Practical nonparametric statistics. John Wiley & Sons Inc., New 
York. 
Dorris, P. R. 
1970. Spiders collected from mud-dauber nests in Mississippi. J. Kan- 
sas Entomol. Soc. 43 : 10-11. 
Eberhard, W. 
1970. The predatory behavior of two wasps, Agenoideus humilis (Pom- 
pilidae ) and Sceliphron caementarium (Sphecidae), on the orb 
weaving spider Araneus cornutus (Araneidae). Psyche 77: 243- 
251. 
Eibl-Eibesfeldt, I. 
1970. Ethology: The biology of behavior. Holt, Rinehart and Winston, 
New York. 
