The Mountain Pine Beetle in British Columbia

The current outbreak of mountain pine beetle in British Columbia is the largest that Canada has ever seen. This map depicts the area affected by the infestation, based on aerial overview surveys conducted in the late summer and early fall of 2006.

The mountain pine beetle, Dendroctonus ponderosae Hopkins, is a member of the group of insects known as bark beetles. Endemic in lodgepole pine stands throughout western North America, the mountain pine beetle is normally limited to highly stressed trees within the pine forest ecosystem.

However when the right circumstances align, such as large areas of over mature pine and several years of warm winters, outbreaks make it the most destructive insect pest of mature pine forests.

Mountain pine beetles normally attack mature or weakened lodgepole pine (80 years old or older).

They lay eggs under the bark, and when larvae feed on the inner bark of the tree they cut off the supply of water and nutrients. The beetles introduce a bluestain fungus that holds back a tree’s natural defences against the attack by killing living cells in the inner bark and sapwood. The larvae and fungus combination girdles (kills) most attacked trees. The fungus also discolours the sapwood of the trees and devalues the wood. If beetle infested trees are harvested within two or three years of attack, they retain most of their economic value.

Many other forest values can be affected by mountain pine beetle infestations and outbreaks including:

impacts on landscape aesthetics
impacts on water quality
changes to wildlife habitat
future reduction of Allowable Annual Cuts
possible decline in property values,; and
potentially higher-intensity forest fires and loss of investments.

It takes a number of years for an outbreak to develop. The current outbreak in central interior British Columbia is a product of the following three conditions:

a landscape with an abundance of susceptible trees
sustained favourable weather, and,
a lack of effective control action during the outbreak’s incipient stage.

The major outbreak of the mountain pine beetle in the west-central interior of British Columbia has been present for approximately 10 years but the infestation has increased rapidly in recent years to become the largest in the province’s history.

A winter low of -40°C or a sudden cold snap in early fall or late spring of -25°C would reduce beetle populations enough to end the outbreak.

More information on the mountain pine beetle in western Canada: