Many studies of parasitoid-host or predator-prey dynamics have considered the problem of when a natural enemy should leave a resource patch. This is an important question in biological control because the timing of natural enemy dispersal can affect the ratio of natural enemies to pest both within a patch and throughout a region. Because short-lived arthropods, such as predatory mites, are not likely to acquire information about the regional distributions of their resources (which, furthermore, change all the time), these foragers probably rely on local environmental stimuli which may provide adequate, but not necessarily optimal, information. Decisions about when to disperse are based on innate behaviors which may be modified by local environmental cues such as prey density. For example, some individuals of the predatory mite Phytoseiulus persimilis disperse while prey are still available, but most will stay until almost all prey are consumed. At a population level, earlier predator dispersal may be associated with a longer local interaction period and higher overall prey numbers. We developed a quick bioassay to measure variability in the rate at which individual P. persimilis left prey patches with different levels of resources. Using this bioassay we observed the effects of predator starvation and experience on leaving rate, as well as the intrinsic dispersal tendency which varied among individuals.