Abstract: Laboratory tests were conducted in Beijing on the infectivity of 3 species and 5 strains of the entomopathogenic nematode, Steinernema spp. on the overwintering larvae of Eucryptorrhynchus chlnensis [Col.: Curculionidae], a pest of the important ornamental tree, Ailanthus altissima. Two Chinese strains of S.feltiae, strains A₂₄ and Beijing, caused 100% and 90% mortalities of the larvae 8 days after the treatment. The larval mortality for Beijing Strain reached 100% by the 14th day after the treatment. Mortalities of the larvae infected with the other 3 strains tested were all about 90%. The results also showed that the larval mortality increased as the soil water content increased in the range of 10-20%. On the 5th day of the treatment, the larval mortality was 70% in the soil of 20% water content. The mortality was 45-50% when the soil water content was 10-15%. Infection of the weevil adults caused only 15% mortality. In a field trial of controlling E. chinensis and another weevil, E. brandti, infesting the Ailanthus trees in the suburbs of Beijing, the A₂₄ and Beijing strains gave control effects of 77.3% and 70.0%, respectively.