Protecting Forests from Pine Beetle Outbreaks

By Jennifer Hunt (Content Writer), Nicole Porter (District Manager), and Brian Vrablick (Intermountain Region Manager

Tiny beetles but massive destruction—pine beetle outbreaks can turn thriving forests into tree graveyards. Pine beetle outbreaks, particularly those involving species such as the Western pine beetle (Dendroctonus brevicomis) and the mountain pine beetle (Dendroctonus Ponderosae), pose significant threats to forest ecosystems and the forestry industry. Effective prevention and management strategies are crucial to mitigate their impact. Continue reading to learn which management strategies foresters use and how they prevent pine beetles from taking over forest land.

Before digging into pine beetle prevention, let’s examine where these pests live and the conditions they thrive in.

Western pine beetle:

• Range from California through Oregon, Washington, and Idaho, and east through Montana, Utah, and Colorado
• Prefer ponderosa pine and Coulter pine
• When the weather warms up, beetles are on the move, looking for their next victim. They bore through the bark and create egg galleries under the bark, where eggs are deposited along the margins of the galleries. One of the early signs that a tree has been attacked is "pitch tubes," which are created by the tree as a defense response.

Mountain pine beetle:

• Range from Alberta and British Columbia, Canada, through Northern Baja California and Idaho and Montana to Arizona and New Mexico
• Prefer lodgepole, ponderosa, western white, sugar, limber, and whitebark pines
• Temperature plays a large role in when and how many Mountain pine beetles emerge, regardless of adaptation to cold and heat

The Western pine beetle typically requires two strategies, namely suppression and prevention. Suppression focuses on removing infested trees. Because adult Western pine beetles can fly long distances to mate, it’s crucial to treat all trees in an extensive area. Prevention, on the other hand, involves thinning trees in healthy stands to further contribute to overall vigor. This reduces competition and makes the trees stronger against any potential beetle attacks. For the mountain pine beetle, both long-term and short-term strategies are available to foresters and land managers. Short-term strategies include the use of synthetic pheromones. Synthetic aggregative pheromones function as “bait,” attracting beetles to a small infestation site so that they can be contained. Foresters also use anti-aggregation pheromones to protect a stand of trees during an outbreak, which functions as a shield around the area. This is best done in conjunction with the planned removal of infested trees. Long-term prevention relies on silvicultural practices such as thinning and prescribed burning. Thinning in ponderosa and lodgepole pine stands achieves several goals, including dissipating the beetle-based pheromones through open crowns and providing nutrients, water, and additional growing space for the remaining trees.

Pine beetle outbreaks can devastate forests, but proactive management strategies help prevent infestations and protect valuable timberland. Careful management of a stand by a professional AFM forester keeps beetle risk very low, preventing a reactionary response. By implementing thinning practices, utilizing pheromone-based control methods, and carefully managing forest health, landowners and foresters can minimize the risk of beetle outbreaks. While these tiny insects pose a major threat, strategic forestry practices ensure resilient, thriving forests.