Bark Beetle: The Forest Fire Follower

The 2017 wildfires in California have broken some very serious records. According to CNN, this year’s fires are “the costliest,” with estimates of over $10 billion in damages, “the most acres burned in California in the last 5 years,” “the worst for air pollution in the Bay Area,” and lastly, “the biggest in modern California history.” As if these weren’t bad enough, there is a destructive pest that thrives on the charred carnage of these fires. That pest is the bark beetle.

 

What is a bark beetle?

A bark beetle is a small wood-boring insect that cuts off the supply of vital nutrients to trees by tunneling underneath the bark. Though they may be little (about the size of grain of rice), they are fierce…to trees at least. To humans, bark beetles are just a nuisance. Their reproductive abilities are part of what makes bark beetles such a problem. One pair of beetles can give birth to over 12 million babies in one year, so infestations can happen quickly.

 

Bark Beetles and Forest Fires

Though many studies have shown that bark beetles do not necessarily cause forest fires, the reverse may be true. Forest fires are often a significant driving force behind bark beetle infestations. Fires do not always kill trees, but instead, leave them in a weakened state. These weakened trees are very attractive to bark beetles, who look for trees that are, in essence, not strong enough to fight them off. The 2017 forest fires in California have left plenty of trees susceptible to bark beetle attack.

 

Signs of a Bark Beetle Infestation

Signs of a bark beetle infestation can be seen both in the bark and in the leaves or needles.

Tree Bark

Here is what to look for:

  • Small pitch tubes on outside of bark
    • Resembles sap and may be white or red/brown in color
  • Frass, much like that of termites, left behind as the beetles chew through bark
    • Resembles sawdust or coffee grounds
  • Holes left by woodpeckers hunting for bark beetles
  • Needles will turn reddish-brown starting from the top of the tree and traveling downward

 

Bark Beetle Damage

It can take as little as 2-4 weeks for bark beetles to kill a European oak bark beetle, Scolytus intricatus, extreme close-uptree. As they bore through the tree bark, the bark beetles lay their eggs. The larvae then feed on the living tissues of the host tree, leaving it unable to transport nutrients to all parts of the tree.

The U.S. Forest Service reports that bark beetles have killed over 29 million trees and have destroyed 45 million acres of forest in the western United States alone. Normally, bark beetles help to renew the forest by killing off diseased and weakened trees.

However, when forest fires are leaving many burned trees in their wake, there are many more weak trees for bark beetles to attack. Healthy trees are better equipped to fight off bark beetles by exuding pitch which forces the beetles out. Trees take varying amounts of time to die after bark beetle infestation. But once trees appear dead, they can no longer be saved, so it is important to watch for early signs of infestation.

 

Bark Beetle Treatment

Because bark beetles reside underneath the bark, it can be difficult to control them with insecticides, especially DIY methods. Sprays and other chemical treatments are most effective as a preventative measure and not as a treatment solution. Once bark beetles have begun an infestation, it is best to get the professionals involved. Full removal of the trees or shrubs may be necessary.

 

Am I at risk for bark beetles?

Bark beetle activity is highest in spring and summer. Luckily, they do not infest wood without bark, so homes are usually safe. However, if you have a log home, you may be at an increased risk for bark beetles, particularly if the logs on your home still have the bark.

Though your home may be safe, the trees on your property are not immune to bark beetle infestation. If you think you may have bark beetles in your trees, take particular caution, as the trees may be severely weakened. Depending on the severity of the infestation, the bark beetles may have already done a significant amount of damage, which would increase the possibility of tree collapse.

Check out the tree mortality viewer created by the California Department of Forestry and Fire ProtectionC to locate the most high-risk areas.

 

Preventing Bark Beetles

Preventing bark beetles entails a great deal of planning. Trees should be planted far enough apart that they are not fighting against each other for water, light, and other resources. As previously mentioned, bark beetles do not infest wood without bark, so the most common way they are brought into the home is through firewood, as they are attracted to wood that has been freshly cut. Bark beetles can remain in a tree for up to a year after its death, so make sure to check your firewood for the aforementioned signs of a bark beetle infestation.


If you suspect that you have a bark beetle problem, don’t wait. Bark beetles move fast, so you should too. Give the experts at Western Exterminator a call or contact us online today.

 

Ashley Smith

Ashley is a Digital Content Manager with Rentokil. She loves drinking coffee and spending time with her dogs.

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