The search for effective biological control of mites in Pennsylvania apple orchards began in the late 1960's. During the 1970's, the coccinellid mite predator, Stethorus punctum, was found to be tolerant of some organophosphate insecticides and was conserved using alternate-row middle pesticide applications. It gave effective biological control of spider mites until the mid-1990's when new pesticides and acaricides were registered for tree fruit. Phytoseiid predatory mites then became more abundant in apple orchards and began to give effective biological control of spider mites. Initially Neoseiulus fallacis was most abundant in apple orchards, but in the last 3 years, Typhlodromus pyri, has been found for the first time. Through conservation and augmentation programs, T. pyri has begun to replace N. fallacis, and is a more effective biological control agent. New predatory mite species found in 2005-6 have the potential to supplement the biological control of spider mites in Pennsylvania apple orchards in the future.