Differential Predation on Cocoons of Hyalophora Cecropia (Lepidoptera: Saturniidae) Spun on Shrubs and Trees

The cocoons of Hyalophora cecropia (L.) were found at various heights on the branches of trees or close to the ground on the stems of shurbs in urban environments in Champaign and Urbana, Illinois. Over 81% of the pupae in cocoons on shrubs survived the winter to emerge as adults. Less than 4% of the pupae in cocoons on trees survived, over 86% having been killed by birds, almost certainly woodpeckers. Cocoons on trees are exposed while those on shrubs are usually well hidden. We suggest that the differential destruction of pupae on trees may be a recent phenomenon caused by characteristics of the urban environment, and that it would be reasonable to look for a rapid selection against spinning on trees.