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Invasive Species: Mountain Pine Beetle

A dark brown beetle at the center of a pinkish-white plug of pitch that's emerged from the rough bark of a pine tree.

Invasive Species: Mountain Pine Beetle

Watch list - not detected

This species is on Michigan's invasive species watch list but has not been detected in Michigan.

What is mountain pine beetle?

(Dendroctonus ponderosae Hopkins)

Mountain pine beetle is an aggressive and destructive bark beetle that can infest most pine tree species. The beetles and their larvae tunnel through inner bark, eventually causing tree death.


What to look for

Since this small (1/4 inch), dark brown to black beetle is hard to identify, look for these signs on any species of pine trees:
Popcorn-like globs of brown, pink or white pitch on the tree’s trunk.
Red frass, resembling fine sawdust, on bark crevices or at the tree’s base.
Yellow to red needles in the tree’s crown in the summer.
Evidence of woodpecker feeding, such as missing patches of bark.
Galleries under the tree’s bark.

Mountain pine beetle photos

The following images can help identify mountain pine beetle. Click on each photo for descriptions.


If you find suspected signs of mountain pine beetle on pine trees in Michigan, note the location and take photos to aid in verification. Report your find to:

Species info


Mountain pine beetle can attack pines in large forest areas as well as those in neighborhood landscapes. In the west, its primary host trees are lodgepole, ponderosa, sugar and white pine, but it has been found in other pine species including jack pine and Scots pine. Nearly all species of pine are susceptible to mountain pine beetle. The exception is Jeffery pine. Mountain pine beetle initially may attack weak or damaged trees but then will move to nearby healthy trees as the infestation spreads.


Native: Mountain pine beetle is native to western North America, ranging from Northern Mexico to Canada and eastward to the Black Hills of South Dakota.

U.S. Distribution: Mountain pine beetle is known to occur in Arizona, California, Colorado, Idaho, Montana, Nebraska, Nevada, New Mexico, Oregon, South Dakota, Utah, Washington and Wyoming. It also occurs in the Canadian provinces of Alberta, British Columbia and Saskatchewan.    

In Michigan: The mountain pine beetle has not been detected in Michigan.

Local concern

Mountain pine beetles burrow into pine trees to mate and deposit eggs. Larvae tunnel under the bark, eventually killing the tree. These beetles carry harmful fungi that are released when they enter a tree. This blue stain fungus interrupts the tree’s nutrient and defense systems and leaves characteristic discoloration in the outer wood.  In western states and Canada, mountain pine beetles have caused the loss of 125 million acres of coniferous forests.

Michigan’s 20 million acres of forest land support a $20 billion forest products industry. The value of pine timber resource is estimated at $3 billion.  Native pines including red, jack and the state tree, white pine, are an important part of landscapes and ecosystems across the state. Widespread establishment of mountain pine beetle has the potential to cause severe damage to Michigan’s environment and economy.  

How it spreads

The mountain pine beetle can be introduced or spread by transporting infested trees, logs, lumber, firewood or plant parts. Once present, mountain pine beetles rapidly infest nearby trees.

Quarantine information

The Michigan Department of Agriculture and Rural Development’s Mountain Pine Beetle Exterior Quarantine regulates the movement of firewood and pine products with bark attached from states with infestations of mountain pine beetle.


Once mountain pine beetle infests a tree, nothing practical can be done to save that tree. Good forest management is key mitigating conditions favorable to this pest. Mountain pine beetle prefers forests that are old and dense. Managing the forest by creating diversity in age and structure with result in a healthy forest that will be more resilient and, thus, less vulnerable to attack. Certain pesticides have been shown to be effective in killing beetles or deterring attacks on individual trees under low population levels. These are less effective when high population outbreaks occur.