Lygus hesperus in California and L. lineolaris in the southeast US cause considerable economic damage to cotton. Previous attempts to control Lygus with a commercial strain of the entomopathogenic fungus Beauveria bassiana have resulted in inconsistent results. The commercial strain was isolated from an aphid in the Northeast US and may not be particularly adapted to the cotton belt climate and native isolates may be more active against Lygus. Previously, we reported recovery and characterization of multiple Lygus isolates of B. bassiana. Two isolates, one from California and one from Mississippi were field tested in 2004 and 2005 to determine if use of these isolates could impact Lygus populations in cotton and/or surrounding source host plants. Results of these tests will be presented.