Field and laboratory observations on oviposition by Euploea core (Insecta: Lepidoptera)

Oviposition behaviour of female Euploea core butterflies, a polyphagous species, was examined in the field and the laboratory. In the field females oviposited eggs singly on Nerium oleander and Parsonsia straminea. On N. oleander most eggs were laid on flowers and very young leaves. On P. straminea (none of which were flowering) very young leaves were favoured. In both species most eggs were laid on the undersurface of plant structures. Eggs tended to be located in the upper portions of plants, which reflects the general distribution of young foliage and flowers. This was more pronounced in N, oleander (a bush) than P. straminea (a vine). The distribution of eggs among both species was clumped. Height of N. oleander plants appeared to have no effect on oviposition, and neither did the distribution of plants. N. oleander plants in the shade were favoured above those in exposed positions. Plants of pink-, white- or red-flowered varieties were equally likely to be used. In the laboratory females oviposited on all plants offered from the families Asclepiadaceae, Apocynaceae and Moraceae, with N. oleander and P. straminea receiving many eggs. Asclepias species were sometimes highly favoured for oviposition, although these species are not suitable for larval development. No evidence was found for the prior presence or absence of eggs on plants influencing subsequent oviposition, nor was any evidence found for a marking pheromone influencing oviposition