Answer: Japanese maples are among the more common hosts of the Asian ambrosia beetle (Xylosandrus crassiusculus), with other hosts including styrax, ornamental cherry (especially Yoshino), pecan, peach, plum, dogwood, persimmon, sweetgum, magnolia, fig, Chinese elm and azalea. This pest is attracted not only to damaged, stressed or transplanted trees, but to seemingly healthy trees as well. The beetle becomes active in early March (or earlier), and the female beetles bore into trunks or branch wood of thin-barked hardwood trees. Once a tree has been attacked, it becomes more attractive to further attack. Often these trees are less than four inches in diameter. Visible symptoms include wilted foliage, as well as the toothpick-like strands of boring dust (frass) that protrude from these small, pencil-lead size holes. The Asian ambrosia beetle does not feed upon the wood of the host, but instead carries with it an ambrosia fungus, which grows within the galleries made by the beetle. This fungus serves as a source of food, and may partially be responsible for the death of the host plant.
Prevention and Treatment: Heavily infested plants should be removed. If only a few braches are infested they may be cut out. The life cycle takes approximately 55 days until the emergence of the next generation of beetles, so prompt removal or burning of the wood is important. Protective sprays of other susceptible plants may reduce their spread. Permethrin (such as Green Light Borer Killer, Bonide Borer-Miner Killer, or Astro) may be used as a trunk and scaffold limb spray. Thoroughly wet the bark. Multiple treatments may be needed during a season. Research indicates that spraying the infested trunks with permethrin may cause the beetles to leave the galleries they have already created.
Best wishes with your tree!
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