Some of the most important predators of mites are the predatory mites, including the western predatory mite, (Galendromus occidentalis), Euseius species, and Phytoseiulus species. Predatory mites have longer legs and are more active than are the plant-feeding mites. They move much faster and lack the dark spots of spider mites. You can purchase and release predatory mites to establish populations, but the best results are obtained by creating favorable conditions for naturally occurring predators—for instance, by avoiding dusty conditions and pesticide sprays.

Predator mites do not feed on foliage or become pests, so must be released when pest mites are available. To establish predators in a heavily infested orchard or garden that has few predators, use a soap spray to bring pests to a lower level and then release predators. A good rule of thumb is that one predator is needed for every ten spider mites to provide control. Concentrate releases where spider mite numbers are highest. Once established on perennials, predatory mites may reproduce and provide biological control indefinitely without further augmentation unless nonselective insecticides are applied.