Xylotrechus aceris

Hosts: Maple. Red maple is favored. Silver maple, sugar maple, and Norway maple are also attacked.

Damage: Visible evidence of infestation is swellings or gall-like formations on otherwise smooth stems. Bark begins to break away at the entrance, exposing wood darkened by decay. Fine yellowish frass may be present at gallery entrances. Dissection of infested stems reveals a small cavity under the bark and a gallery 7 to 12 mm in diameter extending 5 to 12 mm horizontally into the stem, then turning 8 to 13 cm straight up. Attack sites sometimes resemble disease cankers. Young saplings 4 to 7 cm in trunk diameter, particularly those in the understory, are most susceptible, but attack sites have been found in trunks up to 10 cm in diameter. Attack sites are most common in trunks but sometimes occur in branches of larger trees.

Adults leave round exit holes, 4 to 5 mm in diameter usually in the galled, distorted bark near entrance sites. Swollen, irregular scars that remain on the stems for several years are evidence of previous attacks.

Range: Eastern US south to NC and GA and west to MI and in southern Canada

- James D Solomon: (1995) Guide to Insect Borers in North American Broadleaf Trees and Shrubs^©