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Mountain pine beetle
and related bark beetles

Mountain pine beetle, Dendroctonus ponderosae, is an insect native to the forests of western North America.  Previously called the Black Hills beetle or Rocky Mountain pine beetle, periodic outbreaks of the insect can result in losses of millions of trees.  Outbreaks develop irrespective of property lines, being equally evident in wilderness areas, mountain subdivisions, and back yards.  Even windbreak or landscape pines many miles from the mountains can succumb to beetles imported in infested firewood.

Mountain pine beetles develop in pines, particularly ponderosa, lodgepole, Scots (Scotch), and limber pine.  Bristlecone and pinyon pine are less commonly attached.   During early stages of an outbreak, attacks are limited largely to trees under stress from injury, poor site conditions, fire damage, overcrowding, root disease, or old age.  However, as beetle populations increase, mountain pine beetle attacks may involve most trees in the outbreak area.

A related insect, the Douglas-fir beetle (Dendroctonus pseudotsugae), occasionally damages Douglas-fir.  Most often, outbreaks are associated with previous injury by western spruce budworm.  spruce beetle (Dendroctonus rufipennis) is a pest of Engelmann and blue spruce in Colorado.  Injured pines also can be attacked by the red turpentine beetle (Dendroctonus valens).

Pine Beetle

Ips Beetle

Mountain pine beetles, and other bark beetles in the genus Dendroctonus, can be separated from other bark beetles by the shape of the hind wing cover.  In side view, it is gradually curved.  The wing cover of Ips or engraver beetles, another common group of bark beetles attacking conifers, is sharply spined.  In Scolytus beetles, such as the shothole borers and European elm bark beetle, the area under the wing cover (abdomen) is indented.

Mountain Pine Beetle Update

When treating pine beetle infested logs, the most common treatment has always involved the use of the insecticide "Lindane."  Sometimes the logs are covered with plastic as well.  Since the last beetle outbreak on the 1970's, Lindane has been banned in most forms.  Because of this, and to be more environmentally friendly, we now use a solar treatment on infested logs as outlined by the U.S. Forest Service. 

Pine Beetle Winter Identification

The best time to check for Pine Beetle attack is in winter.  Check for "pitch tubes" on the trunks of your trees.  If you see pitch tubes, cut a piece of bark off and see if the wood under the bark is discolored bluish-gray.  If so, the tree(s) need to be removed.

Lam Tree Service is available in winter to inspect your property for beetles.  We charge an hourly fee for this service.

For more information, click on the following link: Mountain Pine Beetle

Quick Facts

Mountain pine beetle is the most important insect pest of Colorado's pine forests.   Pine beetles kill large numbers of trees annually during outbreaks.

Trees that are not growing vigorously due to old age, crowding, poor growing conditions, drought, fire or mechanical damage, root disease and other causes are most likely to be attacked.

For a long-term remedy, thin susceptible stands with emphasis on leaving well-spaced healthy trees.

For short term controls, spray, burn, and peel attacked trees to kill the beetles.   Preventive insecticide sprays can protect green, unattacked trees.

Signs and Symptoms of Mountain pine beetle attack

Popcorn-shaped masses of resin, called "pitch tubes," on the trunk where beetle tunneling begins.  Pitch tubes may be brown, pink or white in color.

Pitch Tubes

	Boring dust in bark crevices and on the ground immediately adjacent to the tree base.
	Evidence of woodpecker feeding on trunk.  Patches of bark are removed and bark flakes lie on ground or snow below tree.
	Foliage turning yellowish to reddish throughout the entire tree crown.  Usually occurs either to ten months after a successful pine beetle attack.
	Presence of live beetles (eggs, larvae, pupae, and/or adults) as well as galleries under the bark.  This is the most certain indicator of infestation.  A hatchet for removal of bark is needed to check trees correctly.
	Blue stained sapwood.  Check at more than one point around the tree's circumference.

Infested Trees

	Once mountain pine beetle infest a tree, nothing practical can be done to save that particular tree.
	Under epidemic or outbreak conditions, enough beetles can emerge from  an infested tree to kill about two same-sized trees the following year.
	Ips and related beetles that emerge early in summer often are mistaken for mountain pine beetle, leading to early reports that "mountain pine beetle is flying."  Be sure to properly identify the beetles you find associated with your trees.
	Trees from which mountain pine beetle have already emerged (look for numerous round, pitch-free exit holes in bark) do not need to be treated.
	The direction and spread rate of a beetle infestation is impossible to predict.  However, attacked trees usually are adjacent or near previously killed trees.

Lam Tree Service, Inc.
P. O. Box 2486
Evergreen, CO 80437-2486
Phone:  303-674-8733      Fax:  303-674-1968