Entomopathogenic fungi were sampled from soils at four adjacent ecosysystems (vegetable crop soil, oak forest, chaparral, and pine reforestation) at Saltillo, Mexico, in the Chihuahuan desert. Beauveria bassiana was statistically more abundant in oak forest soil. Metarhizium anisopliae was more abundant in agricultural soils. We isolated more than 100 strains of entomopathogenic fungi from all habitats. Selected strains varied widely in their virulence against greenhouse whitefly Trialeurodes vaporariorumand thrips Gynaikothrips spp., and some strains were highly active. Soils at these locations are a reservoir of abundant strains of fungi with potential as applied biological control agents.