Bark, beetles, wildfires, and the Yosemite National Park (California. USA)

If you don’t live in or near California, you may not have heard about our drought, and our relentless wildfires, which now start sometime in the beginning of the summer and only end with the first rains, sometimes well into October. These fires typically affect the chaparral scrubland of the lower elevations, but they have become more frequent and more intense in the Sierra Nevada, where the well-known Yosemite National Park is located.

Although I have been to Yosemite some five times since I moved to California fifteen years ago, I still remember how highway 120, one of the access roads to the park, looked on my first trip: a lush green coniferous forest. It now has been replaced, in many areas, by a charcoal wasteland. Last time I went up to the park following 120, back in the beginning of April of this year, I took the time to stop and take a few snapshots of the destruction (see featured image).

What happened in Yosemite?


Native bark beetles kill many trees in California, but the level of damage they cause is primarily influenced by tree density (trees in dense groups are more vulnerable to bark beetle infestation) and forest health. In and around Yosemite, we have a combination of densely packed conifer trees, and poor forest health resulting from several years of water deficit and poor forest management. Diseased and dead trees, from beetle attacks, are a great fuel for wildfires which, in Yosemite, are often ignited by lightening. The fires spread very fast among the dead trees, also killing, and burning the healthy trees on their path.

Patch of burnt trees along highway 120 towards Yosemite

Bark beetles bore through the tree bark to lay their eggs in the inner bark. They feed on the living tissue of the tree, cutting off its ability to transport nutrients. The pattern on the underside of the bark, created by the feeding of these insects, is characteristic of each species. Good photos of beetle galleries can be seen o this post by fellow blogger Steve Schwartzman. I took the photo below in Yosemite.

Remains of bark beetle galleries on a burnt tree

One clue that a tree has been infested by bark beetles is woodpecker holes. Woodpeckers make holes in the trunks to find food and eat the larvae that are beneath the surface of the tree bark. This time in Yosemite, I witnessed several Douglass Fir pine trees with many woodpecker holes on them.

Base of a pine tree with woodpecker holes.

Most likely, we will end this spring in another water deficit. The snowpack in Yosemite this year is about 64% of its long-term average amount. I am not looking forward to another summer of wildfires in the Sierra Nevada, but it looks like we are on our way to it.   


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10 thoughts on “Bark, beetles, wildfires, and the Yosemite National Park (California. USA)

  1. Steve Schwartzman says:

    Those are sad-looking forests in your first two pictures. On television last night we saw that wildfires had burned down mansions in Laguna Niguel, south of Los Angeles. I thought a La Niña weather pattern might account for your drought—and maybe it has contributed in recent years, but the article at

    predicts northern California will be on the wet side of average this year, and the middle of the state average. In contrast, a southern band across the United States is expected to be drier than average due to La Niña.

    Liked by 1 person

  2. jodifrye says:

    Wow !! Being in the northeast we do hear about and see the wildfires on the news for your area but ya know that’s as far as it goes. We never hear about the bugs. Seeing the results in your photos certainly makes it more personal and educational. I learn from you. But ya know nature does its thing and adapts as it goes. Looks so bad to us mere bipedals but it is the circle of life. It never ends. I recall how much cleaner they noted our world became when the pandemic stopped us in our daily tasks of destroying the planet. Nature will always win.


  3. jim hughes says:

    The black-and-whites really tell the story. I have to believe those forests will recover, but it might take several (human) generations. We need to stop development that encroaches on them, and learn to just leave them alone.

    Liked by 1 person

  4. Steve Gingold says:

    Here we have a pine bark beetle that is destroying a red pine woodland in the Quabbin Reservoir lands. Not at the level your top image shows as we so far haven’t had forest fires of any magnitude near what California does, but the trees are dead and falling to rot on the ground. Just as with your Yosemite forest, I will not see those pines like they once were again. Our time scale and nature’s are vastly different and it is possible that it may be centuries before forests regenerate. Here in New England most of the original old growth has been cut and in some cases the second growth as well starting in colonial times for Britain’s great masted naval fleet and then during the age of agriculture here. So that’s roughly four centuries of history.There are still a few pockets of old growth though not many. But the forests do grow back…eventually.

    Liked by 1 person

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