Abstract
Cryptomeria japonica trees were thinned in mid November and the stems were either left non-bucked, or bucked to 1 or 2 m. All stems were then left on the forest floor until early May of the year after the next. The stems, 6 m from the butt end, were then placed in a netted room. The sapwood moisture content, the number of emerged adults of Urocerus japonicus and the number of oviposition holes were examined. The numbers of oviposition holes and emerged adults were markedly lower in bucked trees than in non-bucked trees. Since there was no difference in survival rate, the number of emerged adults appeared to depend largely on the frequency of oviposition. On the other hand, the sapwood moisture content of trees bucked to 2 m was higher than that of non-bucked trees, suggesting that the moisture content of the host wood affects ovipositional behavior.
