Insect Borers and Willow Acacia

Growth Habits

• The Willow acacia grows 20 to 40 feet in height with a 15-foot canopy width. It is rounded, spreading or weeping in shape with a growth rate of 36 inches each season. Its sword-shaped linear leaves are blue-green or dark green. The tree bark is light or dark gray and furrowed or rough. Willow acacia pods are more than 3 inches long with showy orange or yellow flowers blooming in spring or late winter.

Uses

• This hardwood tree has traditionally been used to make furniture and as fire fuel. It spreads quickly through airborne seed dispersal and sprouts in the root system. It is considered a weed in some areas and is often used in dry landscapes with clay, sand or loam soil. It grows in slightly acid to highly alkaline soil conditions.

Willow Borer

• The poplar-and-willow borer is a beetle insect of the genus Cryptorhynchus and the species lapathi. It attacks poplar, alder and birch trees but its favored host is willow. The adult beetle is black with an irregular band of gray or pink scales. It has a long, curved snout and generally grows to about a half-inch in length from C-shaped creamy, white larva with a brown head. The larva feeds on the willow tree interior wood.

Damage

• Larvae burrow into the tree’s inner bark and begin to feed on tree stems. They excavate extensive tunnels, weakening the tree over time. Damage is observed as irregular splits and holes in the bark. Sap and moist red-brown and white shavings exude from the splits. Shavings may also be seen around the base of the tree stems. Previously damaged areas may have darkened tunnels and calloused holes or splits.