Abstract
From the result of measuring the number of damaged trees, the number of damaged portions per single tree, the number of galleries in xylem and their length, and the number of emergence holes, sanbusugi was superior to kumotooshi in resistance to the Cryptomeria bark borer (Semanotus japonicus LACORD.). It is possible to estimate the length of galleries in the xylem by observation of gallery traces in the bark and from the correlation coefficient between the length of gallery traces in the bark and the length of galleries in the xylem. The mean age of trees attacked by the Cryptomeria bark borer was 12.7 years. When a tree was damaged before it was 13_??_14 years old, the extent of the attacked portion was greater than in trees older than this. The width, depth, length, and volume of colored or decayed parts in the xylem of kumotooshi were larger than those of sanbusugi. Futhermore, the colored or decayed parts below 6m in kumotooshi overlapped each other and were distributed continuously up and down the trunk.
