Food plant defoliation and larval starvation of Euphydryas editha

Investigation of larval food plant relationships of populations of Euphydryas editha Boisduval throughout California demonstrated three striking phenomena. First, relationships between butterflies and plants were found to be highly variable among populations utilizing different (but related) food plants. Second, defoliation of food plants was quite common and often extensive; this is contrary to the widely accepted generalization that herbivores rarely defoliate their food plants. Third, larval starvation was the rule, occurring to some extent in most of the populations investigated.