Black Turpentine Beetle
Introduction
The black turpentine beetle (Dendroctonus terebrans) is the largest of the pine beetles and is most often a secondary pest. It can be found living in pines that have been previously infested by the southern pine beetle, freshly cut pine stumps or weakened or stressed pine trees.
Identification
Adult black turpentine beetles are dark reddish brown to black and have a stout, cylindrical shape that ranges from 5/16 to 3/8 inches long. The larvae are a long, legless brown headed grub that can reach ½ inch long with brown bumps on the sides of its body.
Turpentine beetle attacks are characterized by occurring at the base of the tree, usually within 6 feet of the ground although some attacks have been noted up to 15 feet high. The majority of new attacks occur from spring to fall. The beetle is attracted to the resin odor coming from bruised bark or freshly cut trees. Tree symptoms include fading of the needles from green to yellowish green to reddish brown and 1 inch sized pitch tubes around the base of the tree. The pitch tube will have a hole in the center if the beetle attack was successful. Egg galleries are usually in the shape of a reverse J or an upside down question mark (?). Once hatched, the larvae begin feeding on the phloem in fan or D shaped galleries which may only weaken the tree. If the number of successful attacks increase over time, nutrient movement is obstructed and tree mortality occurs. The black turpentine beetle also carries blue stain fungus that interferes with nutrient and water movement as well.
Current Situation
Black turpentine beetle presence is reported every year throughout the pine regions of Tennessee but rarely affects more than a few pine trees. If favorable conditions arise, the black turpentine beetle populations may increase and cause larger scale mortality. This however is most likely to occur in after a previous infestation by a primary bark beetle such as southern pine or Ips beetle.
Annual Survey
No formal trapping program is conducted throughout Tennessee for the black turpentine beetle. Forestry personnel are trained to recognized signs and symptoms of black turpentine beetle attacks and work with forest landowners to educate them on ways to make their woodlot healthy and resistant to major black turpentine beetle attacks.
Management Options
Keeping pine trees healthy is the best way to prevent black turpentine beetle attacks. Although drought, flooding, lightning strikes, etc. are uncontrollable, correct tree spacing, timely thinnings, and constant monitoring are things forest owners can do. If an attack does occur and is small (less than one pitch tube per inch of tree diameter), no control measures are necessary. However, the eggs and grubs can be mechanically destroyed either by scraping away the bark below the pitch tube to expose the galleries or take a rubber mallet or crushing the pitch tubes. Chemical controls are available to protect trees from becoming re-infested. Contact your local forester, extension agent or Division of Forestry personnel for more information regarding chemical treatment.
What Can You Do?
If you own a single pine or a stand of pine, the best thing you can do is keep the pines healthy. Correct plant spacing, timely thinnings, and clean harvesting can prevent black turpentine beetle populations from building. Learn to recognize what the signs and symptoms are of an infestation and immediately contact your county agent, professional forester, or Nathan Hoover with the Division of Forestry. Early detection is very important to preventing major infestations.
