Red turpentine beetle
Pines that have been stressed by drought, insects, fire, logging, root damage or other site disturbances can be attacked by red turpentine beetles, Dendroctonus valens. These beetles prefer to attack the lower trunk in contrast to other bark beetles of red pine which initiate attack in the upper crown. They feed on the phloem (live tissue) of the inner bark and their chewing destroys the cambium and scars the face of the sapwood. When red turpentine beetles attacks are numerous, nutrient conducting tissues are destroyed and the tree is weakened further. The presence of this pest is indicated by pitch tube formation on the bark near the base of the trunk, particularly the root collar. Each pitch tube is irregularly shaped, turns white to reddish as it hardens and has a hole in its center that is the only entrance to the beetle's chambers.
Reversal or correction of stress conditions may prevent tree mortality. In Crow Wing County, red turpentine beetles first appeared in pheromone traps on May 27th.