North American gypsy moths disperse as newly hatched larvae on wind currents in a behavior called ballooning. Because ballooning occurs before neonates begin to feed, resources used in dispersal are limited to those carried over from the egg. We show that nutritional experience of the maternal parent can influence the tendency of offspring to disperse, and that resource provisioning of eggs by the maternal parent affects the duration of the window for disperal. Offspring of females from defoliated sites had a lower tendency to balloon in a wind tunnel than larvae from females which had not experienced nutritional stress associated with host defoliation. The number of eggs in an egg mass, a reflection of the maternal parent's nutritional experience, also contributed to the predictive model for dispersal that included defoliation level. Egg weight and the levels of two yolk proteins, vitellin (Vt) and glycine-rich protein (GRP), however, had no influence of the proportion of ballooning larvae. The length of survival without food, and thus the maximum period of time for dispersal, was correlated with levels of Vt and GRP, but not with egg weight. The level of defoliation at the site from which the maternal parent was collected was not related to the longevity of offspring, nor did it have a significant effect on the levels of Vt, GRP or egg weight. Levels of hemolymph proteins arylphorin and vitellogenin in the maternal parent during the prepupal stage had no influence on levels of yolk proteins, larval longevity, or tendency to balloon.

1 Predation by small mammals has previously been shown to be the largest source of mortality in low-density gypsy moth, Lymantria dispar (L.), populations in established populations in north-eastern North America. Fluctuations in predation levels are critical in determining changes in population densities.2 We compared small mammal communities and levels of predation on gypsy moth pupae among five different oak-dominated forest types along this insect's western expanding population front in Wisconsin. Comparisons of predator impact can provide critical information for predicting variation in susceptibility among forest types. 3 The results indicated that small mammals caused more mortality than did invertebrates. 4 Both abundance of Peromyscus sp. predators and predation levels were lower in urban and xeric forest types than in mesic sites. 5 These results suggest that, because predation pressures will probably be greater in the mesic sites, gypsy moths may be less likely to develop outbreaks in these habitats, and that defoliation will probably be more frequent in urban and xeric oak-dominated sites.