An extensive survey of the San Joaquin Valley of California revealed infection of the Lygus hesperus population with the entomopathogenic fungus, Beauveria bassiana. In some fields more than 50% of the L. hesperus population was infected. Isolates of B. bassiana were cultured and laboratory bioassays completed to determine if any isolates had better activity than a commercial isolate. In a companion study in Mississippi, isolates of B. bassiana were recovered from L. lineolaris. Isolates were swapped between the two labs and additional studies were done. Two isolates were chosen for field application. Results of the California field tests, conducted in June, 2004, will be presented.