20 
Psyche 
[Vol. 88 
cost of predation to the wasps by making capture more difficult, 
more costly, and/or less probable. Natural selection should there- 
fore promote evolution of such anti-predator strategies which in the 
long run increase the fitness of the prey. 
Some components of the system such as flying away and cryptic- 
ity, perhaps regurgitation, are of a very generalized nature whereas 
other devices are more predator-specific. Thus startle displays with 
exposure of dark semi-circular markings are probably most efficient 
against small avian predators, whereas biting, mouth regurgitation, 
hind leg raising and obstruction behaviors are presumably more 
useful against smaller, more vulnerable predators such as other 
insects, including digger wasps. Matthews and Matthews (1978, p. 
352) state that “protective adaptations in insects are intimately 
related to the behavior and physiology of their predators.” This also 
applies well to wasp predators. 
Acknowledgements 
The Arizona study was part of a sabbatical project, while on an 
exchange program with the American Museum of Natural History, 
New York, in 1972-73. Research was conducted at the Southwest- 
ern Research Station, Portal, Arizona, and in the surrounding 
areas, including the Chiricahua National Monument and the Erick- 
son Ranch. Help, advice and hospitality of many persons and 
friends, I cannot mention individually, are gratefully acknowledged. 
Wasp specimens were kindly identified by A. S. Menke, U.S. 
National Museum (Entomology), Washington; R. M. Bohart, Uni- 
versity of California, Davis, and W. J. Pulawski, Wroclaw Univer- 
sity, Poland, and grasshopper specimens by D. C. Rentz, the 
Academy of Natural Sciences, Philadelphia, Pennsylvania. The 
study was supported in part by an operating grant (A3499) from the 
National Research Council of Canada and funds from the Univer- 
sity of Alberta, Edmonton, Canada. I would like to thank J. 
Scheinas for typing the manuscript. 
Summary 
Harmless herbivores such as acridid grasshoppers exhibit a 
complex anti-predator behavior when attacked by Prionyx and 
Tachysphex sphecid wasps. Besides jumping and flying away with 
