Sources of Mortality Among Late Instar Gypsy Moth1 Larvae in Sparse Populations2

Publisher Website
Google Scholar
Abstract
Survival of instar IV–VI gypsy moths, Lymantria dispar (L.), in a sparse and numerically stable population near Eastford, Conn., was inversely correlated with larval density. Larvae that rested in bark flaps during the day were more likely to survive than those that rested in the forest litter. Since few of these insects were killed by parasites or disease, we believe that most of them were eaten by density-dependent predators that can forage in the litter. The results also suggest that predator densities in this particular area were always sufficient to remove most of these larvae, and that resting locations, coupled with prey density per se, were most important in determining this survival rate. In contrast to Eastford, predators were ineffective in containing equally sparse subpopulations at innocuous levels in a general outbreak area near Glenville, N.Y.; apparently, most of the attacks by these predators were absorbed by the prey insects in nearby, more dense subpopulations.