Abstract: Pathogen was separated from the bodies of infected Euproctis pseudo-cor.spersa larvae and was identified as Euproctis pseudoconspersa nuclear poly-hedrosis virus (EPNPV). The rod-shaped virus belongs to the multi -granule inclusion type. Its DNA is of the configuration of monomolecu-lar double-strand superhelix,with a molecular weight of 9.6-9.7?107 Dolton.According to the results of bioassey on Euproctis pseudoconspersa larvae (3-5 instar), the LC50 of EPNPV was 1.18-1.58?105 PIB/ml. Large amounts of the virus was obtained by following methods: 1. applying the virus to tea bush and then collecting infected larvae; 2. transferring the infected larvae to a tea plot for reproduction; 3. reproducing on laboratory conditions.Formulations of powder and emulsion were made for field experiment. According to the field experiment conducted since 1976 on different instared larvae under various ecological conditions, a control rate of 71 -97% was observed in a dose of 3-6?107 PIB/ml, with some persistent effect.During 1985 and 1986, about 4000 mu of tea plantation was treated with EPNPV. The control rate was 82-90% or more. Significant economic benefits were reaped. EPNPV is safe to humans and animals and not toxic to such main predators as spiders and ladybugs.