Abstract
Phytoseiulus persimilis and Amblyseius californicus were released into commercial field corn in the Texas High Plains in 1982 and 1983. Both predators significantly reduced spider mite infestations and maintained these infestations below economically damaging levels. Timing of releases was critical to the efficacy of the phytoseiids. Plots treated with P. persimilis generally had lower spider mite densities than did plots treated with A. californicus, though statistically significant differences were detected on only one occasion.