Management Options

Small infestations can be eliminated through quick action, such as the removal of infested trees. Residents should inspect pine trees in the fall after mountain pine beetle adults fly to new host trees. After the beetles infest a tree, the best practice is to remove the tree by the following spring, ensuring infested wood is disposed of properly to avoid spreading the beetles.

Large outbreaks of mountain pine beetles are difficult to control. One of the best ways to mitigate the effects of beetle outbreaks is to manage for overall forest health and resiliency. Thinning overly dense stands of trees to reduce competition and promote tree age and species diversity is the most successful forest management strategy to increase tree vigor.

Strategies for managing mountain pine beetles

• Removal of infested trees and slash from thinning or pruning will prevent beetles from emerging and flying to new trees. Continual removal of trees already affected by other insects or diseases, as well as trees in overly dense areas, should be prioritized, as beetles most frequently attack unhealthy trees. Residents should contact their local transfer station or landfill to dispose of infested wood and slash, or search online for local wood drop-off locations or businesses that may utilize the material. Do not move infested wood unless you intend to drop it off at a secure location as it could spread the beetles.

• Solar treatments can be used to reduce mountain pine beetle populations in small, infested stands. These treatments involve felling infested trees, stacking cut logs off the ground in an area with full sun and covering them with clear plastic. The solar treatment of infested trees creates conditions unsuitable for the survival of the beetle’s larvae.

• Trap trees serve as traps for recently emerged, adult beetles. After the trap trees become infested with beetles, the trees are removed and destroyed, usually during the fall or winter while all of the beetles are still inside.

• The use of pheromone packets containing verbenone, known as semiochemicals, disrupts the attraction of incoming beetles and can be used to reduce attacks on pine trees where no other management options are effective (e.g., in proximity to water or near structures where overspray of preventive insecticides may be undesirable). The effectiveness of verbenone has been much debated in the scientific literature, though recent advances in altered concentrations have proven effective when beetle pressure is low. Consult the CSFS Forest Health Team for more detailed information on using pheromone applications.

• The use of preventive insecticide sprays may prove effective in preventing mountain pine beetle infestation. Specific formulations of pyrethroids that are registered and tested for effectiveness are the primary preventive insecticidal sprays used to help reduce the likelihood of attacks on individual trees. The Colorado State Forest Service recommends spraying only high-value trees, such as those near homes, businesses or recreation sites. Follow the label of any chosen product.