Asian Ambrosia Beetle in Japanese Maple: Sawdust Toothpicks Signal Infestation

Tiny Beetles Farm Fungus in Your Maple

A Japanese maple shows ½–1 inch sawdust "toothpicks" protruding from bark, with gray-tan frass and tiny larvae. Bark peels off.

Females bore into stressed trees, inoculate ambrosia fungus, lay eggs. Larvae eat fungus, not wood. Sawdust tubes = entry/exit holes.

Pyrethroid spray on trunk/branches (bifenthrin, permethrin) when beetles active (spring, 70°F+).
Systemic: Limited efficacy—beetles don't eat vascular tissue.
Sanitation: Remove and destroy heavily infested limbs.
Health: Water, mulch, avoid wounding—beetles target stressed trees.

Contact state forestry agency (free in most states) for confirmation and local timing. NC State fact sheet: ces.ncsu.edu/.../note111.html

Trees: Japanese Maple Wax Scale: Identification and Systemic Treatment Options; Clustering Insects on Tree Branches: Scale or Beetles?; 'Inaba Shidare' Japanese Maple: Identification and Container Growing Guide; Japanese Maple Bark Peeling: Often Normal Exfoliation; Bees Swarming Japanese Maple: They’re After Aphid Honeydew; Fireglow Japanese Maple: Size, Sun Tolerance, and Care in Denver; Staking and Patience for Lopsided Japanese Maple; Planting Japanese Maple in Clay Soil with Hardpan; Why Propagating Japanese Maples at Home Isn't Practical; Japanese Maple Long Shoots: Natural Growth Habit

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