Abstract: The lesser tea leafhopper, Empoasca vitis (Homoptera: Cicadellidae) is the most serious tea tree pest, which has developed high resistance to almost all insecticides and needs biological alternatives. In the present study, an isolate of Isaria javanicus from Empoasca spp. and 4 isolates of Beauveria bassiana from other leafhoppers were tested for their extracellular protease activity. I. javanicus isolate and two Beauveria isolates were screened out for further bioassay to early instar nymphs of the leafhopper. The result showed that the virulence of I. javanicus isolate was 2.33～7.26 fold and 6.08～27.26 fold higher, respectively, than that of the two Beauveria isolates, with LT₅₀ at 5.9 d under the concentration of 1×10⁸ conidia·mL^-1, which caused 100% mortality on the 13^rd d. IJOD-1, an oil dispersion formulation was developed with the Isaria isolate for field test. The field test with a randomized block design demonstrated that IJOD-1 sprayed at a dose of 7.5×10¹³ conidia·ha^-1 resulted in an efficacy of 50.32% on the 11^th d; the second spray on the 25^th d caused the efficacy of 68.40% on the 55^th d.