Provincial officials tracking the beetle infestation warned in a report that the amount of destroyed trees could reach 150 million cubic metres next year unless the weather turns cold enough to kill larvae before they hatch.

This year's winter in the Cariboo Region where the bugs have hit the hardest is not expected to be particularly cold.

Officials said the number of trees killed in the infested area varies from area to area, but the critical infestation is considered to cover 9 million acres in the province's Interior region, up from 8 million acres last year.

"This is clearly an epidemic of catastrophic proportion," said Larry Pedersen, British Columbia's chief forester.

The tiny beetles lay eggs in lodgepole pine. The insect's larvae then eat the wood just under the bark, which the trees need to supply themselves with nutrients. The trees are usually dead within a year of being infected.

In addition to killing the trees, the beetles also carry a fungus that creates a blue stain in the uneaten wood. The stain does not damage the wood's structural integrity, but makes the timber harder to sell for esthetic reasons.

The beetles have been found in the forests for thousands of years, but their populations have been kept in check by extreme winter cold, which kills the larvae, and by forest fires, which destroy the infected trees before the beetles can spread.

British Columbia has not had a major bug-killing cold snap for several years, and the fires that once raced through the forests each summer are now fought by a multimillion-dollar control effort.

Pedersen said the area of epidemic is now considered to stretch from Fort St. James in northeastern British Columbia nearly 1,100 (715 miles) south to near Cranbrook.