Pine Beetles

The mountain pine beetle, Dendroctonus ponderosae Hopkins, is a member of a group of beetles known as bark beetles. Except when adults emerge and attack new trees, the mountain pine beetle completes its life cycle under the bark.The number of dead pine trees in Discovery is growing and some of our residents have expressed concern that our neighborhood may be infested with pine beetles.

Jay Hein, Colorado Springs City Forrester, visited Discovery in September 2016 to examine some of the dead and dying pine trees along Dry Creek. He believes those trees died of other natural causes, and asked us to pass along that there is little reason for concern about pine beetles in Discovery at this time.

While that assessment is reassuring, we all need to be on the lookout for early signs of any kind of bark beetle infestation. Discovery would not be the beautiful, natural neighborhood we all enjoy if we were to lose our pines! To help you understand what to look for, we've extracted some information regarding pine beetles from one of the reference materials Mr Hein provided, U.S. Forest Service Forest Insect & Disease Leaflet 2, Mountain Pine Beetle. Links to other reference materials can be found below.

Evidence of Infestation

The mountain pine beetle begins attacking most pine species on the lower 15 feet (4.4 m) of the trunk. Trees are generally killed by beetles of a single generation.

However, large sugar pines are first attacked in the crown. Two or more generations of beetles -- each generation attacking a lower portion -- may occur before the tree is killed.

Examination of infested trees usually reveals the presence of pitch tubes. Pitch tubes are made when female beetles bore into the tree. There are two types of tubes. Pitch tubes on successfully infested trees are cream to dark-red masses of resin mixed with boring dust and are 1/4 to 1/2 inch (6 to 13 mm) in diameter. Pitch tubes on unsuccessfully infested trees are larger, 3/4 inch to 1 inch (19 to 25 mm) in diameter, and widely scattered over the trunk. When beetles are not present in sufficient numbers, trees can produce enough resin to "pitch out" beetles as they bore into the inner bark (see above).

                      











Besides having pitch tubes, successfully infested trees will have dry boring dust, similar to fine sawdust, in bark crevices and around the base of the tree (fig. 2). Sometimes, however, infested trees can have boring dust, but not pitch tubes. These trees, called blind attacks, are common during drought years when trees produce little pitch.


Adult beetles feed within the bark before they emerge; when several feeding chambers coalesce, adults occur in groups. One or more beetles will then make exit holes, about 3/32 inch (2.4 mm) in diameter, (fig. 3) from which several adults will emerge. Within 1 or 2 days after emerging, the beetles will attack other trees.


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