By Brad French
DNRC Clearwater Unit 

Melting snow means forest insect pest management


DNRC Photo

Each species of bark beetle leaves a unique pattern that aids in identification. Douglas-fir beetle larvae travel perpendicular and outward from the parent beetle's initial chamber.

Springtime is here, and for a lot of forest landowners it means getting back into the woods on their property for cleanup and upkeep. It also means that forest insects start to show themselves again. Forest insects are found throughout Montana, with some being more of a problem than others depending on conditions. Below are a few facts that may help forest landowners address concerns.

Douglas-fir beetles typically infest damaged, sickly or recently broken Douglas-fir trees. With last year's windthrow, snow breakage and the 2017 fires, there is an expected rise in activity from these beetles. Keep an eye out for fading tops and red boring dust at the base of the tree. Once a tree is infested, there is no way to halt the attack. Cutting and removing infested trees from the area can prevent infestation of adjacent trees if done in a timely manner. Landowners wanting to guard individual trees, such as those closer to their house, can apply anti-aggregation pheromone packets called Methyl-cyclo-hexanone (MCH) prior to April 15th(approximately when beetles emerge and fly to other trees). Please note that not all beetle deterrents target the same insect- do your research before purchasing a product!

Another insect pest that has been gnawing away on our forests is the spruce budworm. These silky little caterpillars feed on young conifer needles found near the tops of trees and in younger trees. While budworms can feed on a variety of conifer species, subalpine fir, Douglas-fir and Engelmann spruce have shown considerable damage in our area. Promoting tree health and maintaining a variety of tree species and size classes is the best tool for controlling these outbreaks, with insecticides being the only other means of physical control.

One last note: Don't move firewood out of region! Moving firewood can spread forest insects into unaffected areas. We already have enough insect pests to deal with and bringing in another pest would be truly devastating. Consider buying locally if you are camping outside of the area. If you do move wood, use it all up or take the extra firewood back home. We can all be a part of limiting the chances of spreading insect pests to where they shouldn't be.

There are a lot of factors that can play into a tree's health. Sometimes insect activity is part of a larger issue that a tree or group of trees is facing.

Please feel free to contact Brad French (406) 244-2382, Clearwater DNRC Service Forester with any questions or for a free forest consultation.


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