Prealighting search behavior and host plant selection by ovipositing Euphydryas editha butterflies.

A montane California population of butterflies was studied at 2 sites in adjacent habitats. In each study site, only one host plant species was used by the butterflies; in one site the host was the annual Collinsia torreyi, in the other it was the perennial Pedicularis semibarbata. In the Pedicularis study site, butterflies discriminated in favor of the host both by searching in areas where it was dense and by alighting preferentially on host plants. In the Collinsia study site, no evidence of a significant prealighting discrimination towards hosts was obtained. The suitability of Collinsia as a host has increased recently, but the butterflies have not yet evolved behavioral mechanisms of prealighting search that would enable them to locate these plants efficiently. -from Author