Resource concentration and herbivory in oak forests

Larvae of the fall cankerworm (Alsophila pometaria), a polyphagous defoliator of canopy trees, hatch at the time of budbreak of scarlet oak (Quercus coccinea), about 10 days before budbreak of white oak (Quercus alba). Thus the Alsophila population was dense in a site dominated by scarlet oaks and defoliated the scattered white oaks when they came into leaf. In a site dominated by white oaks, the Alsophila population was sparse and chiefly attacked scattered scarlet oak. Thus in each stand, the rarer species of tree suffered greater herbivory, in-contrast to the more commonly reported observation that herbivore attack on a plant species increases with density.