Mountain pine beetle (MPB) is an insect native to the forests of western North America and is also known as the Black Hills beetle or the Rocky Mountain pine beetle. MPB primarily develop in pines such as lodgepole, ponderosa, Scotch and limber pines, and less commonly affect bristlecone and piñon pines.

Mountain Pine Beetle Affected Trees in the Red Needle Phase

2015 Aerial Survey

Mountain pine beetle (Dendroctonus ponderosae) activity subsided and remained low with a total of 5,000 acres of active mountain pine beetle infestation detected in the state in 2015.

The epidemic has ended in many areas of Colorado as mature pine trees have been depleted following the outbreak that impacted more than 3.4 million-acres of Colorado forestland from 1996-2013.

Many of the pine forests impacted by the outbreak, especially in portions of Middle Park and North Park, now have a gray cast due to the large numbers of dead trees.

Localized Activity

Infestations in both ponderosa and limber pines continued at moderate to low levels on the eastern slopes of the Sangre de Cristo Range, and large groups of limber pines were killed in portions of the western slope of the range from the Cottonwood Creek Basin north to Hayden Pass.

Infestations also occurred on the southern slopes of the San Juan Mountains near Durango, and localized attacks were observed in lodgepole pine stands in the Cochetopa Hills west of Saguache.

Area Infested by Mountain Pine Beetle and Spruce Beetle in Colorado, 1996-2015

Symptoms of Mountain Pine Beetle Infestation

Popcorn-shaped masses of resin, called pitch-tubes, which may be brown, pink or white in color, will be found on the trunk where the beetle began tunneling. Boring dust may be found in bark crevices or on the ground immediately adjacent to the tree base.

Evidence of woodpeckers feeding on the trunk may indicate MPB infestation. Patches of bark may be missing where the woodpecker was feeding, and bark flakes may be found on the ground below the tree. These symptoms are similar to the ips beetle, so be sure to properly identify the beetles you find associated with your tree before deciding on treatment.

Management Options

Logs infested with MPB larvae can be treated in various ways to kill developing beetles before they emerge as adults in summer.

  1. Burning, burying, chipping or removing infested logs
  2. Solar treatments

Learn More About Mountain Pine Beetle

For more information about areas impacted by spruce beetle and other insects and diseases on Colorado’s forests, read the 2015 Report on the Health of Colorado’s Forests.