Oviposition and establishment of Uraba lugens (Walker), the gum leaf skeletoniser

SUMMARY Selection of hosts by Uraba lugens (Walker) involves two distinct patterns of behaviour. In choosing egg sites, females appear to select a particular quality of leaf, blue-green to dark-green in colour and with firm maturing or mature surfaces. Young soft leaves, yellow or yellow-green and overmature foliage rarely attract oviposition. It is possible that tactile or chemical signals from the leaves dominate this selection process which occurs during low light intensities. The adult provides the site at which the ecloding larvae must establish but the egg-hosts include highly suitable food plants as well as species which militate against either establishment or survival of caterpillars. Selection of any potential host by first instars occupies about two days following eclosion and involves behaviour patterns from ready acceptance and mass feeding through feeding that is not sustained to dispersion of the larval group and no attempt to feed. Feeding trials have consistently supported field evidence of the suitability of egg-hosts for larval establishment and survival. Some trees, consistently avoided as oviposition sites in natural situations have been readily accepted as food plants, in the laboratory, by larvae following eclosion.