46 
Psyche 
[Vol. 92 
plant choice of these hybrid larvae, indicating little or no genetic 
variation among individual females in their hostplant choice behav- 
ior. These results are in contrast with those of Tabashnik, et al. 
(1981), which showed significant genetic variation among individual 
females of Colias eury theme, and Singer (1982) who found similar 
genetic variation in oviposition preference among individual females 
of E. edit ha. 
Thus there is clearly a genetic component to the hostplant prefer- 
ences exhibited by larvae of Euphydryas. However, the variation 
among individual females found by Tabashnik, et al. (1981) and 
Singer (1982) was not evident here, although the sample sizes were 
small. The preferences exhibited by the larvae are not absolute as 
larvae of both species did feed on the alternate food offered. These 
preferences may be important in the colonization of new population 
sites as well as in the incorporation of new hostplants into the 
existing repertoire of a particular population. 
Acknowledgments 
Location of populations and collection of larvae was greatly 
aided and enhanced by David McCorkle, Sterling and Eileen Mat- 
toon, Ken Hanson, and Kay Pearse. Karen Schwartz provided 
excellent and enthusiastic laboratory assistance. Paul Ehrlich, Gil- 
lian Puttick, Nancy Stamp, and Bruce Tabashnik were extremely 
helpful in their comments on the manuscript. This work was sup- 
ported by NSF grant 83-07353 to D. Bowers and NSF grant DEB 
78-22413 to P. R. Ehrlich. 
References Citkd 
Bauer, D. L. 
1975. Tribe Melitaeini. In: W. H. Howe. The Butterflies of North America. 
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1983. Divergence in larval responses to food plants between temperate and 
tropical populations of the black swallowtail butterfly. Ecol. Ent. 8: 
249-257. 
Bowers, M. D. 
1979. Unpalatability as a defense strategy of checkerspot butterflies with spe- 
cial reference to Euphydryas phaeton (Nymphalidae). PhD thesis. Uni- 
versity of Massachusetts. 
