The mountain pine beetle, Dendroctonus ponderosae, is a small insect, less than a centimeter long, which lives most of its life under the bark of pine trees, including lodgepole, ponderosa and western white pine.

Normally these insects play an important role in the life of a forest. They attack old or weakened trees, speeding the development of a younger forest. However, unusual hot, dry summers and mild winters in central British Columbia during the last few years, along with forests filled with mature lodgepole pine, have lead to an epidemic. To date, beetles have destroyed millions of lodgepole pine in BC – the province’s most commercially harvested tree.

During late summer, adults leave dead trees and seek out and attack living green trees. They bore through the bark to get at the phloem – the sweet juicy region that carries sugars from the pine needles to tree roots. Here they create galleries for their eggs. Eggs hatch within a few days and larvae mine outwards from the parent gallery girdling the tree.

Adult beetles like to attack large-diameter trees. Bigger trees provide higher quality food and larval habitat than smaller trees and their thicker bark provides greater protection from predators and climatic extremes. However, large-diameter trees in a stand tend to be more vigorous and have a greater capacity to resist attack. As beetles try to bore through the bark of healthy pines, the tree produces large amounts of resin as a defense. The tree may overcome attacking beetles and literally 'pitch' them out as seen here.

The beetles also carry spores of “blue-stain” fungus in their mouths. As they chew on the tree fungus spills out and begins to shut down the tree’s pitch production. The mutual network of beetle galleries and blue-stain fungi disrupts the defenses within the tree, quickly killing it.

Woodpeckers like to feed on the larvae, but during an epidemic the woodpeckers aren’t able to keep the insects under control. The biggest threat to the beetle is the weather; temperatures below –40°C and sudden cold snaps below –25°C in early fall or late spring are needed to kill the beetle.

You should look for:

Yellow or red needles on the entire tree crown. (Needles fade from green to yellow and then to bright red.) Note – discoloration occurs during the year AFTER attack when the beetle has almost completed development. By the time trees appear bright red, the beetles have left to attack new trees.

Galleries (tunnels beneath the bark) with beetles, eggs or larvae.

"Pitch tubes" -- globs of resin on the trunk where beetles tunnel into the bark.

"Sawdust" at the base of a tree or in bark crevices.

Woodpecker activity, such as holes in the trunk and bark chips on the ground.

Are there treatments I can use to help manage the beetle?

There are a variety of treatment options to consider.

(Note – you should consult with an expert before conducting treatments.)

Prevention: Healthy, vigorously growing trees are most resistant to attack. The most effective way to prevent a mountain pine beetle infestation is to harvest mature lodgepole pine trees and pine dominant stands before they become over mature (generally over 80 years old). Consider spacing or thinning large groups to allow individual trees better access to moisture and light. Soil moisture affects the degree to which trees are drought stressed, and stressed trees have limited capabilities to produce the resins necessary to ‘pitch’ out invading beetle.

Felling and Burning: Felling and burning of individual infested trees is a commonly used tactic for killing the beetles where wood recovery is not practical. The fire must be hot enough to completely burn the bark and the stump of the infested tree. (Check burning regulations and always follow appropriate safety requirements.)

Felling and Debarking: Another approach is to fall and then remove the bark of attacked trees. Bark must be removed along the entire length of the tree in which there are beetles or their larvae. This can be done in the spring and early summer (before July) when the bark is loose. Remember to also debark the stumps above ground level.

Replanting: Maintaining the values of your property will require a rehabilitation strategy. Replacing trees involves preparing the site by removing brush and creating suitable planting spots. Of course, your selection of tree species is important and pine certainly should be considered. Trees should be planted with adequate spacing and measures taken to ensure that they remain healthy.

Pesticides: Some types of insecticide can be used to protect trees. Timing and application techniques are critical. Seek the advice of local forestry or environment officials. Permits and approvals from government agencies are required.

The mountain pine beetle, Dendroctonus ponderosae, is a small insect, less than a centimeter long, which lives most of its life under the bark of pine trees, including lodgepole, ponderosa and western white pine.

Normally these insects play an important role in the life of a forest. They attack old or weakened trees, speeding the development of a younger forest. However, unusual hot, dry summers and mild winters in central British Columbia during the last few years, along with forests filled with mature lodgepole pine, have lead to an epidemic. To date, beetles have destroyed millions of lodgepole pine in BC – the province’s most commercially harvested tree.

During late summer, adults leave dead trees and seek out and attack living green trees. They bore through the bark to get at the phloem – the sweet juicy region that carries sugars from the pine needles to tree roots. Here they create galleries for their eggs. Eggs hatch within a few days and larvae mine outwards from the parent gallery girdling the tree.

Adult beetles like to attack large-diameter trees. Bigger trees provide higher quality food and larval habitat than smaller trees and their thicker bark provides greater protection from predators and climatic extremes. However, large-diameter trees in a stand tend to be more vigorous and have a greater capacity to resist attack. As beetles try to bore through the bark of healthy pines, the tree produces large amounts of resin as a defense. The tree may overcome attacking beetles and literally 'pitch' them out as seen here.

The beetles also carry spores of “blue-stain” fungus in their mouths. As they chew on the tree fungus spills out and begins to shut down the tree’s pitch production. The mutual network of beetle galleries and blue-stain fungi disrupts the defenses within the tree, quickly killing it.

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