Abstract
Boring of Platypus querciuorus and mortality of the bored trees were investigated in two newly damaged forests by the beetle in Kyoto Prefecture. Rate of trees bored by the beetle was high on both Quercus crispula and Q. serrata, and the density of the entry holes was also high on these trees. The density of entry holes increased with the diameter of trunk for these two tree species, and was not different between the two. However, the mortality of the bored trees was higher on Q. crispula than Q. serrata. From these results, it is cleared that the beetle prefer to bore into the larger trees of both Q. crispula and Q. serrata, and Q. crispula is likely to be killed by the infestation of the beetle rather than Q. serrata. At one of the two study sites, the damage spread out from the area where both thinning forest and girdling of oak trunks to kill them had been done. At another study site, the damage spread out from the area where thinning forest had been done. These suggested that tree felling with remaining the large Q. crispula trees raises the mass mortality of oak trees.
