Abstract:In 1981, the NPV of Aporia crataegi was first discovered in Harbin, Heilongjiang Province, China. Since the mortality is height, the NPV has certain value in the biological control of Aporia crataegi.The inclusion body is spherical, cubic or irregular, with a diameter of 1.0—2.1μm. Each virus bundle consists of 1—12 virus particles. The virion is rod-shaped with a size of 260 40nm.A bioassay of the NPV on 3rd and 4th instar larvae has shown that LC(50) of 3rd instar larvae is 1.4×103PIB/ml; y=3.472+0.488x. LC(50) of 4th instar larvae is 3.4×104; y=3.212+0.395x.In the field, NPV was sprayed with a concentration of 104, 106, 103PIB/ml to control the 4th and 5th instar larvae. The results indicated that the mortality is 71.4%, 90% and 100% respectively, while the natural mortality of the virus disease is 12.7%.