The ‘edgeeffect’ in butterfly oviposition: causality in <i>Anthocharis cardarnines</i> and related species

Abstract

Abstract. 1. An ‘edge‐effect’, where outlying host plants receive proportionately most attention from insect herbivores, is described from the literature, and from data on Anthochoris cardamines (L.), in northern England. 2. Six hypotheses are examined as explanations for the effect in A.curdamines . Four are shown to be refuted by studies on female behaviour and the survival of larvae. 3. It is argued that the ‘edge‐effect’ comes about due to two or more aspects of the searching behaviour of females. The effect may be seen as an outcome of behaviour adapted to searching for host plants of low density.