Gypsy moth Lymantria dispar (L.), is one of the main pests for ornamental and forest trees in U.S, Asia and some parts of Europe (Cannon, 1993; Farrar and Ridgway, 1995), which is considered as a major leaf eater of fall trees in overall northern hemisphere (Elkinton and Liebhold, 1990; Fast and Regnier, 1984). Gypsy moth is the main pest for forest trees in the whole world (Brown, 1984; Gribko et al., 1998). It entered to America from Europe accidentally in 1868 or 1869 and gradually spread out in west and south of the country, rapidly covering most forests of East of America and Canada (Little, 1972). The regions of America where well covered by it and have been led to severe fatality of host trees, destruction of living environments, and heavy expenditures to fight (Kleiner et al., 1995) gypsy moth, which long lasts in the forests of Iran, was seen first in Gilan forests by (Afshar, 1937). Chemical control ever conducted against that always has resulted in ultimate failure, dangers of pollution of living environment and demolition of natural enemies, reduction of especially, poisonings for humans and domestic animals. Therefore, thanks to the numerous problems of chemical control, non-chemical control measures, especially biological control must be seriously studied. Many species of natural enemies on gypsy moth have ever been identified throughout the world; some of which have practically been used for biological control of the pest (Leonard 1968 and 1970 ) .