Abstract: The present paper reports the results of transplanting two species mermithid nematodes, Agamermis xianyangensis Xu et Bao and Hexamermis agrotis Wang et al into corn fields to control insect pests At the end of April, four pregnant mermithid nematodes per square meter were transplanted into the trial plots of corn fields The infective rate of Agrotis ypsilon Rottemberg was 16. 1% in May At the end of August the infective rates of Oedaleus infernalis Saussure, Atractomorpha sinensis Bol , Oxya chinensis (Thunberg), Acrida cinerea Tnunberg, Shirakiacris shirakii (Bol ) and Trilophidia annulata Thunberg were 10.9%, 18.1%, 17.0%, 21.0%, 22.2% and 33.3% respectively Soil investigation in November showed that the density of mermithid nematodes was 33.3 per m³ of soil in the experimental plots Indicating that the nematodes population has settled.