Tetranychus urticae (Koch) (Trombidiformes: Tetranychidae) is a cosmopolitan spider mite species that infests more than 900 species of plants, including commercial species. Tetranychus cinnabarinus (Boudreaux) is characterized by a red coloration, in contrast to the green-colored T. urticae. Both are occasionally found coexisting in warm environments, and, for that reason, they are considered by some to be synonyms. In this study, we identified specimens of the two morphospecies using optical and electron microscopy and amplification of a segment of the mitochondrial cytochrome oxidase I (COI) gene. Bioassays determined the level of susceptibility and survival of both morphospecies when they were infected with the entomopathogenic fungus Neozygites floridana (Weiser and Muma). For the evaluation of the susceptibility of these morphospecies to N. floridana, bioassays were conducted under conditions of 25 ± 2°C, 60 ± 5% relative humidity, and a 12:12-h photoperiod regime. From these bioassays, we found that T. cinnabarinus was less susceptible to N. floridana and that there is a higher level of fertility, survival, and development in the T. cinnabarinus than in the T. urticae mites. Within a mass rearing system, T. cinnabarinus appears be a more efficaceous functional food for predatory mites, such as Phytoseiulus persimilis (Athias-Henriot) (Mesostigmata: Phytoseiidae), than T. urticae to support rearing and release of biological agents for integrated pest management.