PRELIMINARY STUDY ON THE LIFE HISTORY OF THE OIL PINE CATERPILLAR (DENDROLIMUS SPECTABILIS BUTL.) IN SHANTUNG PROVINCE

In Shantung province, the oil pine caterpillar is mainly distributed in Jiaotung peninsulain hilly place and in the South-central part of the province. It attacks mang Species of pinesand especially prefers 10--20 Year-old Japanese red pine which is sometimes severely injured. It occurs one generation each year, the larval stage varies from 8 to 9 instars, the 4thand 5th instars larvae hibernate in winter. Adults emerge in July and August of thefollowing year. The hibernating larvae come down from the pine tree and hide themselves under debrisabove the ground. In the next spring when the average temperature reaches above 10℃,the larvae become active and climb up the tree trunk. Most cocoons are formed at thetree top, but a few scattered on the tree trunk or on other shrubs. The female mates once only in her life. The average number of eggs reaches as highas 950, and nearly 60% of the eggs are laid in the night shortly after copulation takesplace. The longevity of the adult is about 7 days on the average, but the unfertilized female may live 10 days. Many Species of natural enemies are found: Mands and ant; Anastatus sp. andTrichogramma sp. are mainly the egg parasites; Apanteles sp. and Campoplex ProximusForster are parasitic on the larvae. Besides, several parasitic flies from the pupae remainto be determined.