Red turpentine beetles
Although Dendroctonus valens are the largest and most widely distributed bark beetles on the continent, outbreaks are rare and quite localized. They are primarily attracted to stressed pines here in Minnesota and commonly build up in trees already infested with other species of bark beetles, like Ips pini, another species that attacks stressed pines. Unfortunately, red turpentine beetles seem to prefer the large, old red and white pines.
Branch It is often the attack of other bark beetle species that lead you to look for evidence of red turpentine beetle activity. Flagging and needle discoloration are most common symptoms of bark beetle attack. Red turpentine beetles attack the inner bark of root collar and stump areas up to six feet from the ground. You'd never know they were there except for the pitch tubes they create to provide fresh air for breathing and boring dust disposal. These pitch tubes are quite resiny, speckled with bark and frass particles, are yellowish white in color and are two inches wide or less. Internal evidence of attack are the long, narrow (one inch by three feet) egg galleries and the larval feeding galleries ( up to one foot wide) in the inner bark. The sapwood may be lightly scored.
Similar to other bark beetles, red turpentine beetles attack trees wounded or stressed by construction activities, like paving, regrading, trenching or root smothering. So, damage can be prevented by avoiding these activities within forty to fifty feet of the large pines. Beetle activities can be mitigated by a series of management practices; watering, fertilizing, trapping out the beetles (using pheromone traps) and insecticide treatment of the attacked stems. Probably the most important practice is to water the trees to keep them healthier so bark beetles, of any species, aren't successful in either attacking the tree or in laying eggs inside the tree. Watering is especially important this year after the droughty and very stressful spring and early summer weather.