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How are bark beetles connected to forest fires?

Forest fires leave behind more than just scorched landscapes and heavy smoke; they create the perfect conditions for certain pests to thrive, especially bark beetles. These small but destructive insects are known to take advantage of trees that have been stressed, weakened, or killed by fire. 

Once bark beetles infest these damaged trees, they bore into the wood to lay their eggs, which can lead to widespread tree death and make it even more difficult for forests to recover. Their presence doesn’t just affect the trees, either; bark beetle outbreaks can disrupt local ecosystems, threaten habitats for wildlife, and increase the risk of future infestations if not properly managed.

What are bark beetles?

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.

What is the bark beetles’ role in 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.

According to the Western Fire Chiefs’ Association, climate change is also intensifying bark beetle infestations by creating hotter, drier conditions that weaken trees and accelerate beetle population growth. These infestations increase the risk and severity of wildfires by killing large numbers of trees, fueling the wildfires.

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

If you notice these signs, you may be dealing with a bark beetle infestation. Our technicians at Western Exterminator can inspect the area and help you take the right steps to protect your trees.

How do bark beetles cause damage?

It can take as little as 2-4 weeks for bark beetles to kill a tree. As they bore through the tree bark, the bark beetles lay their eggs. Bark beetle tree damage happens when the larvae then feed on the living tissues of the host tree, leaving it unable to transport nutrients to all parts of the tree.

European oak bark beetle, Scolytus intricatus, extreme close-up

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.

Treatment for bark beetles

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 bark beetle 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.

Who is at risk of bark beetles?

 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. Bark beetle activity is highest in spring and summer. Luckily, they do not infest wood without bark, so homes are usually safe.

Though your home may be safe, the trees on your property are not immune to bark beetle infestation. These beetles mainly target trees, so the biggest risk is to forests, landscapes, and properties with lots of trees, especially pine, spruce, or fir. 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 Protection to locate the most high-risk areas.

Methods to prevent bark beetles

Bark beetle prevention 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.

Understanding what attracts bark beetles is crucial to preventing them. 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.

Frequently asked questions

What are bark beetles?

Bark beetles are small insects that tunnel into trees to lay their eggs. As they move through the bark, they disrupt the tree’s ability to take in water and nutrients, which can lead to serious damage or even tree death.

Where are bark beetles a major problem?

Bark beetles are a major concern in forested areas across the western United States, especially in states like Oregon, Washington, California, and Colorado. They thrive in dry, warm conditions and often spread quickly in areas with large groups of stressed or weakened trees.

How do bark beetles kill trees?

They bore into the bark and create tunnels where they lay eggs. As larvae grow, they continue to feed on the tree's inner layers. This blocks the flow of water and nutrients, slowly killing the tree from the inside.

What types of trees do bark beetles attack?

Bark beetles mainly attack conifer trees like pine, fir, and spruce. However, some species may target other softwoods if the trees are stressed or unhealthy.

What are the signs of a bark beetle infestation?

Look for small round holes in the bark, sawdust-like material around the base of the tree, or reddish-brown dust in bark crevices. You might also see fading or yellowing needles, or patches of bark falling off as the infestation gets worse.

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