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The Study
Life Cycle and Biology
Current Program
No Control Program
Silviculture Program for Young Stands
The Benefits

Mountain pine beetle has been noted as the most serious forest insect pest in British Columbia since surveys began in 1913.

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Mountain pine beetle has been noted as the most serious forest insect pest in British Columbia since surveys began in 1913. The beetle is a natural component of the lodgepole pine ecosystem and serves to recycle forests when they reach maturity. This contributes to forest succession. However, large areas of mature and over-mature pine now exist in the province due to successful fire suppression efforts and other management practices. These stands of pine represent a major component of commercially valuable timber and contribute to a wide variety of other resource uses. They are also at high risk of being attacked and killed by the mountain pine beetle.

    The mountain pine beetle is a small, cylindrical beetle that attacks and kills standing, living, large diameter lodgepole pine. In mid-summer, large numbers of adult female beetles find new trees to attack, bore through the bark to the sapwood and construct vertical galleries under the bark where, after the males join them, they deposit their eggs. These eggs hatch into legless, grublike larvae that feed on the phloem tissue of the host tree. Feeding by the larvae girdles the tree, cutting off the flow of nutrients.

Drawing of the life cycle of the mountain pine beetle.

    Additionally, the beetle introduces a blue-staining fungus into the sapwood of the tree that prevents the tree from killing the beetles with pitch flow, and blocks water translocation. The joint action of larval feeding and fungal colonization kills the host tree within weeks of successful attack. The larvae continue their development under the bark over winter and finally emerge to fly and attack new host material in the summer after the initial attack.

    Outbreaks of mountain pine beetle initially occur in unhealthy, over-mature stands. As more and more trees are infested, the population quickly increases and spreads. Healthy trees are attacked and huge areas of mature pine stands may be threatened or killed. Warm summers and mild winters are advantageous to the insect and play a role in insect survival and the continuation of an outbreak. Adverse weather conditions can reduce the beetle populations and slow the spread, but the insects can recover quickly and resume their rampage.