"You'd have to say there is some reduction in quality due to the beetles," Ketcham told analysts in a conference call on the company's third quarter financial results.

The pine beetle outbreak, which began in the 1990s, has affected more than 8 million hectares (20 million acres) of forests in central and northern British Columbia, killing an estimated 400 million cubic meters of marketable pine, according to provincial government officials.

Forestry experts have warned that without a major winter cold snap, which normally would kill the insect's larvae but which has not happened in several years, the infestation could spread into the neighboring province of Alberta and then Saskatchewan.

Lodgepole and ponderosa pine trees can be logged for several years after they die, but the quality of the wood deteriorates the longer they remain in the forests. Also the beetles carry a fungus that creates a blue stain in the wood.

Tolko Industries last week blamed a decline in the quality of wood as part of the reason it decided to end plywood production at its Kelowna, British Columbia, mill. The mill's stud lumber production will continue.

West Fraser Wednesday reported it had an C$8 million (US$7 million) loss in the third quarter as a weak housing construction market in the United States depressed lumber and building material prices.

Ketcham said more sawmill shutdowns will be required before North American softwood lumber prices improve, but he would not tip his hand on whether West Fraser expects to be idle any of its production.

"Like everyone else, we're intent on a cost-focused culture ... I wouldn't predict how that will sort itself out," he said.

West Fraser's mills are considered among the most efficient in the industry and Ketcham noted none if its facilities were in need of major capital expenditures.