Abstract: April to Aay of each year is the active season of parasitizing of Hexamermis sp.on black cutworm(Agrotis ypsilon rottemberg)and yellow cutworm(Agrotis segetum Schiffermuller). The growth and development of Hexamermis sp.are significantly affected by various environmental factors such as temperature, humidity,solar radition, soil, fertilizer,pH,host,pesticide,etc. ,among which, soil humidity is the major one. The parasitizing rate of Hexamermis sp.varies with soil humidity. Rational application of pesticides,and chemical fertilizers is recommended to protect the Hexamermis sp.and to reduce pollution of the environment.

Key words: polydimethylsiloxane (PDMS), migration and transformation, degradation, ecological effect.