1. In the present paper the author reported the result of his studies on the evaluation of the effectiveness of some egg parasites against Dendrolimus spectabilis Butler, a serious pest of pine trees in Japan. 2. Surveys were carried out at four plots in the Japanese black pine forest situated on the sea coast in the vicinity of Fukuoka City in 1960 and 1961. 3. Six species of the egg parasites were recorded. Trichogramma dendrolimi Matsumura and Telenomus dendrolimi (Matsumura) were common in all plots, and Anastatus bifasciatus (Fonscolombe) was found only in two plots. 4. In summer, Tr. dendrolimi was highly active, and generally the percentage of parasitism of this parasite showed a tendency to increase rapidly two weeks or so after the first deposition of the host's egg. It was, however, pointed out that the population density of Tr. dendrolimi at the beginning of the oviposition period of the host was so low that the greater numbers of host eggs were not parasitized. 5. In autumn, parasitism by Tr. dendrolimi was not observed. On the other hand Tel. dendrolimi was more active in this season than in summer. It is, however, clear that the high percentage of parasitism by Tel. dendrolimi in autumn has little effect on the host population in the next year, because only a small part of the offspring of the summer generation of D. spectabilis emerges in autumn and the rest does in the next year. 6. Parasitism by A. bifasciatus was observed in both summer and autumn, but its population density was always low. 7. Life cycles of the three parasites were discussed in relation to the availability of the eggs of D. spectabilis and other Lepidoptera in the forest. 8. It was concluded that parasitism by the egg parasites in the Japanese black pine forest on the sea coast was not so effective.