Technical Abstract: Several classes of surfactants/foaming agents were screened for compatibility with blastospores of Paecilomyces fumosoroseus. The surfactants were assayed to determine their influence on the rate of germination, viability, and conidia production by blastospores of P. fumosoroseus. Compatible surfactants were then assayed for their foam-forming properties using a commercially available foam generator. These tests identified keratin hydrolysate as the only suitable surfactant in terms of biocompatibility and foam forming properties. Laboratory assays were conducted to determine the effect of keratin hydrolysate on the efficacy of blastospores of P. fumosoroseus against Formosan subterranean termites. The results show keratin hydrolysate increased the efficacy of P. fumosoroseus. A preliminary field trial was performed to test the ability of a P. fumosoroseus foam formulation to control Formosan subterranean termites in infested trees. The results show this foam formulation of P. fumosoroseus is successful in controlling Formosan subterranean termites.