By Katlin Dewitt, VDOF Forest Health Specialist
The southern pine beetle (SPB) is the most destructive native insect that threatens pine forests in the Southeast. These tiny insects, about the size of a grain of rice as adults, are especially harmful due to the complex system of pheromones (insect “scents” that are specific to a species) they utilize to find host trees and aggregate. Pheromones allow populations to build up quickly within a pine stand, often leading to classic beetle spots comprised of dead and dying trees.
The VDOF forest health program monitors SPB populations with traps each spring, starting at the time the redbuds bloom. Traps are placed in high-risk locations (areas with a significant volume of pine) and are baited with pheromones. These traps are checked weekly for four weeks and samples are sorted, looking at the number of SPB and their associated predator, a clerid beetle. The relative number of these two insects is used to determine if southern pine beetle populations are increasing or decreasing. This information allows foresters and landowners to be more alert and act quickly should they see SPB.
In addition to monitoring, certain silvicultural practices can reduce the risk of southern pine beetle attack in a pine stand. Pre-commercial thinning is the most effective management strategy to prevent SPB damage. How can forestry practices influence the population of tiny beetles? A lot of it goes back to those tiny clouds of pheromones the beetles rely on to communicate. When stands are overstocked and densely packed, these “scents” can become concentrated and highly aromatic to the beetles, drawing more and more in, thereby creating an SPB spot. A thinned stand allows more air movement, which breaks up the clouds of beetle perfume and makes beetle aggregation more difficult. Thinning also increases the health of the stand, and healthier trees are better able to resist beetle infestation.
VDOF has a Pine Bark Beetle Prevention Program which is funded by the US Forest Service Southern Pine Beetle Prevention and Restoration Program. VDOF uses this money to operate a cost-share program available to landowners and loggers for specific forest management practices that improve the health of managed pine stands and reduce the risk of SPB infestation. The three cost-share programs offered are: