Studies on the damage of Ambrosia-beetles attacking Chestnut-trees.

Abstract

(1) The experimental researches of the species of chestnut borer par a tree and of attacking places in the trees which were classified by the age were undertaken.
(2) More species of beetles were observed in elder trees. They belonged to the 3 Genera (10 species) so-called “ambrosia beetles”; such as: the Genera of Xylosandrus (1 species), Xyleborus (8 species) and Scolytoplatypus (1 species) at the eleven years old trees.
(3) The species of beetles and the number of attacking holes were more observed in elder trees, but the 3 species of Xylosandrus germanus (BLANDFORD), Xyleborus saxeseni (RATZEBURG) and Xyleborus canus NIIJTMA highly attacked in the young trees and they were seemed to be more injurious than the others.
(4) Almost species of beetles entered by the parts of lenticels, but Xylosandrus germanus (BLANDFORD) and Scolytoplatypus mikado BLANDFORD more attacked into the other parts.
(5) The results of observation of the attacked parts on classified by the age of branches, by high and thickness of trees were as follows:
as the attacking beetles almost parts of the tree…… Xylosandrus germanus (BLANDFORD), Xyleborus saxeseni (RATZEBURG), Xyleborus canus NIIJTMA and Xyleborus laetus NIIJTMA.
as the attacking beetles only the parts of trees being closed to ground…… Xyleborus defensus BLANDFORD, Xyleborus seiryorensis MURAYAMA, Xyleborus validus EICHHOFF and Xyleborus adumbratus (BLANDFORD).
as the attacking beetles only the young branches…… Scolytoplatypus mikado BLANDFORD.