Integrated Pest Management

IPM Manual for Structural Pests in British Columbia

Chapter 10: Powderpost Beetles

Learning Objectives

When you have completed this lesson, you should be able to:

1. Describe the damage caused by anobiid powderpost beetles.
2. Describe how to detect an active infestation of powderpost beetles.
3. Describe measures to prevent powderpost beetle attack.
4. Describe the use of soluble borates to control powderpost beetles.

Identification

Two types of powderpost beetles attack wood in structures: the lyctids or true powderpost beetles and the anobiid powderpost beetles. The insects most commonly called powderpost beetles in B.C. are anobiid beetles. They are usually found damaging softwood lumber in the crawl spaces of older homes.

Anobiids attack hardwoods and softwoods that have higher than normal moisture content, particularly in damp, poorly ventilated crawl spaces. The beetles lay eggs on the wood surface and the larvae bore into the wood. Anobiids usually tunnel within the sapwood, and only occasionally into the heartwood.

Wood attacked by anobiid beetles has round, 2-mm diameter exit holes made by the adult beetles when they leave the wood to mate and lay eggs. Frass, which looks like fine sawdust and feels slightly gritty, can often be seen falling out of the holes. Heavily-damaged wood contains many narrow channels created by the feeding activity of the larvae.

Other types of powderpost beetles attack furniture and hardwood flooring but rarely occur in British Columbia. For more information on identifying these species, consult references listed at the end of the chapter.

Monitoring

The most direct monitoring method is to inspect the exit holes in the wood. If all holes have dark interiors and no frass is seen coming from them, the beetles may have all emerged. If frass is present, however, it shows only that anobiid beetles were once active, but does not provide certain evidence that there is currently an active infestation. Live beetles are rarely seen, even in an active infestation.

A method for finding out whether an infestation is active is to paint the suspect wood, ensuring that all beetle holes are covered. Then check the wood in June, after the adult beetle emergence period, to see if new exit holes have appeared.

Action Decisions

Make sure that the infestation is active before applying controls.

Prevention

To prevent attack by anobiid powderpost beetles:

1. Use kiln dried or air dried lumber in building projects (the drying process kills wood boring beetles).
2. Control moisture levels within a structure, especially in crawlspaces, through ventilation and use of a vapour barrier over the soil under the building.
3. Store firewood away from the house.

Controls

Preferred Pesticides

Borates: Soluble borates (e.g. Timbor®, Penetreat™, Pre-Ser-Vor™, Shell-Guard™) are registered for powderpost beetle control in Canada. Borates applied to the surface of wood prevent attack and kill beetles that are feeding near the surface of the wood. Properly applied, they provide excellent control.

Other Pesticides

Permethrin (Dragnet® and Prelude™) is registered as a spot treatment for powderpost beetle control.

Evaluation

Evaluation consists of inspections to ensure that treatments have been successful.

Further Reading

Bennett, G., J. M. Owens, R. M. Corrigan. 1988. Truman's Scientific Guide to Pest Control Operations. 4th ed. Purdue University/Edgell Communications. 495 pp.

Mallis, A. 1990. Handbook of Pest Control. 7th ed. Franzak and Foster, Cleveland, OH. 1,152 pp.

Olkowski, W., S. Daar and H. Olkowski. 1991. Common-Sense Pest Control. The Taunton Press, Newtown, CT. 715 pp.