BROMMER, J. E., AND M. S. FRED. 1999. Movement of the Apollo butterfly Pmarnssius apollo related to host plant and nectar plant patches. Ecological Entomology 24: 125-131. BROWER, L.. P 969. Ecological Chemistry. Scientific American. 220: 22-29. 1984. Chemical defense in butterflies. In R. I. Vane-Wright and P. R. Ackery (Eds.) The Biology of Butterflies, pp. 109-134. Academic Press, London. AND L. S. FINK. 1985. A natural toxic defense system: cardenolides in butterflies vs. birds. In N. S. Braveman and P. Bronstein (Eds.) Experimental Assessments and Clinical Applications of Conditioned Food Aversions, pp. 171-188. New York Academy of Sciences, New York. CLOBERT, J., E. CANCHIN, A. A. DHONDT, AND J. D. NICHOLS. 2001. Dispersal. Oxford University Press, Oxford, UK. COHEN, J. A., AND L. P. BROWER. 1982. Oviposition and larval success of wild monarch butterflies (Lepidoptera: Danaidae) in relation to host plant size and cardenolide concentration. Journal of the Kansas Entomological Society 55: 343-348. COURTNEY, S. P. 1982. Coevolution of pierid butterflies and their cruciferous foodplants. IV. Host apparency and Anthocharis cardamines~ddd~~~ddd~~~dd oviposition. Oecologia 52: 258-265. AND J. FORSBERG. 1988. Host use by two pierid butterflies varies with host density. Functional Ecology 2: 67-75. G. K. CHEN, AND A. GARDNER. 1989. A general model for individual host selection. Oikos 55:55-65. AND T. T. KIBOTA. 1990. Mother doesn't know best: selection of hosts by ovipositing insects. In E. A. Bernays (Ed.) Insect-Plant Interactions, pp. 161-188. CRC Press, Boca Raton, Florida. CRAIG, T. P., AND T. OHGUSHI. 2002. Preference and performance are correlated in the spittlebug Aphrophora pectoralis on four species of willow. Ecological Entomology 27: 529-540. DEMPSTER, J. P. 1983. The natural control of populations of butterflies and moths. Biological Reviews 58: 461-481. DETHIER, V. G. AND R. H. MACARTHUR. 1964. A field' s capacity to support a butterfly population. Nature 201: 728-729. DIXON, C. A., J. M. ERICKSON, D. N. KELLETT, M. ROTHSCHILD. 1978. Some adaptations between Danaus plexippus and its food plant, with notes on Danaus chrysippus and Euploea core (Insecta: Lepidoptera). Journal of Zoology 185 (4): 437-467.