The author studied the life history and the percentage parasitism of Dolichomitus sp., a parasite of the pine bark weevils, by field observations, and also the development of one generation through laboratory observations. Oviposition was mostly observed on pupae and prepupae of Shirahoshizo spp. and Niphades variegatus ROELOFS from the beginning of July to the end of September. The emergence of the parasite was noted from the end of July to the middle of October. Some larvae overwintered and the adults emerged at the beginning of April. The percentage parasitism to the first generation of Shirahoshizo spp. was 15.8% and that to the second was 27.4%. Egg stage was 2-6 (male) and 2-3 (female) days, the first instar larva-1 (m. and f.), the second-1-3 (m.) and 1-2 (f.), the third-1-2 (m. and f.), the fourth-1-3 (m.) and 1-2 (f.), the fifth-2-7 (m.) and 1-2 (f.), the sixth-3-6 (f. only), pupal stage-2-5 (m.) and 3-5 (f.), and the period from an egg to an adult under laboratory conditions (20-32°C) was 14-21 (m.) and 15-21 (f.) days.