Pine Bark Beetles
Cooperative Extension Service, College of Agricultural and Environmental Sciences, The University of Georgia Bulletin 1097, October 1993, 8 pp.
Black Turpentine Beetles
BTB have rounded abdomens, are dark reddish brown to black, from 5 to 8 mm (1/4 inch) long, and are the largest bark beetles found in Georgia (Figure 6). BTB attacks are normally found on the lower eight- to 10-foot portion of the tree (Figure 4) and produce large pitch tubes an inch or more in diameter (Figure 8).
|Figure 8. BTB Pitch Tube|
Females begin gallery construction and are joined by the males that help excavate egg galleries. Egg galleries normally extend from the point of entry downward and parallel to the grain of the wood.
Females deposit eggs in groups along one side of the gallery. After the eggs hatch, the larvae feed side by-side in large groups during their development, resulting in a "feeding patch" (Figure 9). Fully-grown larvae are about 12 mm (1/2 inch) long.
|Figure 9. BTB Larvae Feeding Group (Patch).|
The BTB life cycle lasts for 10 to 16 weeks, depending on temperature. Three or more generations occur each year in Georgia.
Trees that are not completely girdled by the BTB larvae may survive attacks since BTBs do not carry the blue-stain fungi. Therefore, timely chemical controls applied to BTB-infested trees can kill the larvae and may allow the trees to survive the attack. However, weakened trees are susceptible to other causes of mortality, including other bark beetles.