Alternation of Oviposition Behavior by Battus Philenor Butterflies in Reponse to Variation in Host‐Plant Density

As host—plant density increases, the oviposition rate of Battus philenor butterflies increases, then levels off. By contrast, alighting rates continues to increase with host density approximately linearly. The leveling off of oviposition rates is caused by a decline in the probability that a female will oviposit once she alights on a plant. Evidence is presented indicating that these phenomena are due to an increase in female selectivity as plant density increases, rather than to a limit on oviposition rate imposed by the rate of egg maturation. This type of behavioral response to host density is a mechanism that can explain in part the tendency of many herbivorous insects to aggregate to a greater degree in low—density than in high—density stands of host plants.