Forest Health Protection, Southern Region

Importance. - Ambrosia beetles of the genus Platypus attack most species of pine and hardwood trees. They severely infest weakened and dying trees, green logs, and unseasoned lumber. Trees cut during the summer and left unmilled for more than 2 weeks are often severely damaged. This is especially true of gum, cypress, and oak trees. Ambrosia beetle attacks to green sawlogs and lumber may result in considerable degrade and strength reduction.

Identifying the Insect. - The adult beetles are elongate, dark reddish brown, about 1/4 inch (6 mm) long, and usually have sharp spines at the rear.

Identifying the Injury. - In southern pines, large piles of a fine white granular dust accumulate below the entrance holes or at the base of standing trees. In lumber, the galleries are darkly stained.

Biology. - The adults and larvae do not feed on the wood but on a fungus the beetles carry into the tree and culture in the galleries. The adults bore into sapwood or heartwood of logs and lumber, making pinsized holes which are stained by the fungus. The females lay eggs in small clusters in the tunnel, and the developing larvae excavate tiny cells extending from the tunnel parallel to the grain of wood. There may be several generations a year. Timber is not attacked unless the moisture content of wood is at least 48 percent. Seasoned lumber is never infested.

Control. - No chemical controls are recommended under forest conditions. Rapid utilization of cut timber and fast drying of lumber will prevent damage. Winter harvesting and water storage are also effective.