DENSITY AND PUPATION SITE OF APTEROUS FEMALE BAGWORMS, METISA-PLANA (LEPIDOPTERA, PSYCHIDAE), INFLUENCE THE DISTRIBUTION OF EMERGENT LARVAE

In an oil palm plantation in northeast Sumatra, Indonesia, we tested t he hypotheses that selection of pupation site by female bagworms, Meti sa plana (Walker), influences the distribution of emergent larvae, and that internee dispersal by larvae is density dependant. Similar intra tree distributions of empty female pupal cases and early instars and s ignificant regressions between numbers of female pupal cases and larva e per leaf for 36 out of 39 palms indicated that larvae generally rema in on the same leaf where they emerged. Proportions of early instars p er female pupal case decreased with increasing densities of female pup al cases per tree and were greater on trees surrounding most heavily i nfested palms, suggesting that intearee dispersal of early instars is density dependent. Interspecific comparisons of life history constrain ts between M. plana and the allopatric bagworm Oiketicus kirbyi (Guild ing) reveal different selective pressures that may have converged and favoured the development of an identical life history trait.