Persistent, localized outbreaks in the western tussock moth Orgyia vetusta: the roles of resource quality, predation and poor dispersal

1. On stands of the abundant perennial lupins Lupinus arboreus and L. chamissonis on the California coast, the western tussock moth Orgyia vetusta Bdv. occurs as only a few localized populations, which are locally dense enough to defoliate the host plants and yet do not appear to spread.