Why Colorado's forests are bugging out with beetles

Slide show: Meet the beetles: How Colorado's forests are bugging out

Why Colorado's forests are bugging out with beetles
Jeff Mitton
Beetle-killed trees west of the Eisenhower Tunnel.

Archimedes had his bathtub, Newton his apple. Scott Ferrenberg's Eureka moment required more fieldwork to confirm, but it began when a bug the size of a grain of rice landed on his sleeve as he walked through the woods.

In late May 2008, the graduate student in ecology and evolutionary biology at the University of Colorado was strolling among limber pines at 10,000 feet along Niwot Ridge west of Boulder, home of the university's Mountain Research Station, one of the highest and oldest climate-research facilities in the world. Ferrenberg had no trouble recognizing the visitor on his arm as Dendroctonus ponderosae — the mountain pine beetle, a common sight in lodgepole and ponderosa pine forests across Colorado.

An adult beetle flying around in May on Niwot Ridge, though, isn't so common. Ferrenberg, who was accustomed to studying beetles at lower elevations in California forests, didn't immediately grasp the implications of what he was seeing. "If I'd been told that it shouldn't be there, I might have second-guessed myself," he says now.

But he did think the sighting was unusual enough to report it to Jeff Mitton, a CU evolutionary biology professor with whom Ferrenberg had just started working on a beetle genetics study. Just over a week later — June 8, 2008 — Mitton and Ferrenberg were back at the research site, preparing to dig beetle larvae out of trees for their study. Instead, they found mature beetles diligently assaulting the forest.

"It was a gorgeous day," Mitton recalls. "Shirtsleeve weather. Adults were flying in the air and landing on our shirts. They were hitting the trees and beginning to bore into them. I thought, 'Gee, this is early.'"

Slide show: Meet the beetles: How Colorado's forests are bugging out

Mitton, who's been studying bark beetles since the 1970s, described the scene to an entomologist buddy in the U.S. Forest Service. His friend told him he must be mistaken. Among bug fighters, it was an article of faith that the beetles don't get busy in Colorado until late August. Then they carve galleries into the trees and lay their eggs, which develop from larvae into pupae, then pale yellow adolescents known as teneral — a life spent mostly beneath the bark, until they emerge as pigmented adults late the following summer. Adults flying in June? At 10,000 feet? No way.

Mitton came away from the conversation deeply annoyed. "He was so intransigent about this," he says, "that I realized I must have seen something that's decidedly different from the historic norm."

Over the next two years Mitton and Ferrenberg embarked on a carefully planned study to figure out what was going on. During the winter they identified pristine trees at two sites that hadn't yet been molested by the beetles. They set up lures loaded with pheromones to invite beetles to establish broods in those trees. They visited the sites regularly over the summers of 2009 and 2010 and documented beetles attacking the trees in June and laying eggs. Some of those eggs had developed into a second adult generation by August or September, emerging to seek out fresh hosts and start their own broods.

Early flights of mountain pine beetles have been observed elsewhere in recent years, but the research conducted by Mitton and Ferrenberg — and published in The American Naturalist earlier this year — represents the first peer-reviewed report of the insect achieving two generations in a single summer. The accelerated life cycle, the authors suggest, is a direct response to climate change.

Since the 1970s, warmer weather along the Front Range has allowed the beetle not only to operate in forests above 9,000 feet, where it's scarcely been seen before, but it's more than doubled its flight season, from 50 days to up to 120 days. And the effect on the beetle population is potentially exponential; instead of one female generating 60 offspring a year, those offspring could, in theory, generate an additional 3,600 pine-munching hordes in the same season.

The CU discovery comes in the sixteenth year of an epic mountain pine-beetle outbreak in the western United States and Canada, the worst infestation of its kind in recorded history. In Colorado, what began as a flare-up in lodgepole pine in isolated pockets on the Western Slope in 1996 has left large swaths of doomed, red-needled trees and denuded gray ones across 3.3 million acres, including thousands of ghost trees in popular tourist areas such as Vail, Dillon and Grand Lake. Although the pace of the epidemic has slowed — largely, experts say, because the beetles have already killed most of the large lodgepoles they prefer as hosts — aerial surveys indicate that the affected area expanded by 140,000 acres in 2011, mostly in ponderosa forests in the northern part of the state.

Southern Wyoming has also been hit hard. But then, so have pine forests from the San Bernardino Mountains to the Front Range, from New Mexico to Yellowstone to British Columbia. Western Canada has been particularly pummeled; by some estimates, the pine mortality there has become so extensive, releasing so many megatons of carbon dioxide from tree decomposition into the atmosphere, that it could transform the country's forests from a carbon sink to a carbon source.

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21 comments
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Henderson
Henderson

Please read the article in full. Your comment is off the mark

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Now Pow

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Leola

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Gielsj
Gielsj

This isn't the only study on these, and it has been shown that winters are not cold enough to kill off these bugs

Anthony Beretta
Anthony Beretta

Unless the tree is dead that it can freeze easily. I've seen DEAD wood freeze yearly in the mountains of northern new mexico. So that's why I don't think temperature has a lot to do with this problem.

Bobbert
Bobbert

Nice fixation, Ranger. Lack of forest diversity? Somewhat. Lack of water? Definitely. Longer warm season? Yes. That's what I took from the experts. And experts in Entomology/Forestry are going to be as excited about their subject going up in a mainstream paper as you suggest I am about it. So, I'm not sure which of the indifferent, "who cares" comments you see coming from an expert, or anyone with a degree in this stuff.

Swampfoxcws
Swampfoxcws

So....errr...I suppose the fact that we have not allowed a fire-dependent forest to burn for a hundred years had nothing to do with it? And this climate change thing - what is the climate supposed to be doing? Staying the same? Getting colder? What? We are generally coming out of an ice age, so it is not astounding to me that the climate is getting warmer. Al Gore is making a lot of money on this deal, with his carbon footprint of a thousand city people!

Bob
Bob

Holy long-winded crapology.

Bobbert
Bobbert

Grower: I am absolutely positive that there are other researchers looking for generations of the insects of their choice. I don't doubt that every insect is a major concern of yours as a grower. However, its BS suggesting there is no story (as Phd and others suggested) in the fact that pine beetles have been observed flying for the FIRST time in the Colorado high country in May during a drought which has weakened tree defenses, setting this whole situation up as a potential epidemic...that's a story I am glad is being reported. Regardless of what the other insects are up to. Westword runs gossip pieces and bullshit blogs constantly and no one comments. But here we get a long story that hasn't been regurgitated a billion times, and people are dissing the fact that it was even reported because a small part of the story doesn't jive with their opinion on the narrowest little subject that they know anything about. I stand by my fucking point.

JB
JB

I remember as a kid seeing all the beetle kill trees that were cut down, sprayed, and wrapped in plastic to control their spreading. You could see them on the way up the canyon to Central city on the mountainsides. If this has stopped, the question should be WHY??????

Oliver Philip
Oliver Philip

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Grower
Grower

Ask any farmer and they will agree warm winters increase the yearly chances for multi generations of insects. Are you on the peer review for this article? They plan for this. I agree this is common knowledge. Further, if I planted the same corp every year during an increase of annual multi generation, or single generation, of damaging insects I would be out of business. The lack of forest diversity is the cause and the effect. Climate fluctuations ehances lack of forethought in forest management - the real cause. Examing different type of insects and multi generations of seasonal hatching proves that pine beetles are not exclusive and climate fluctuation increases are in fact common knowledge. Defending someone's thesis, in this case, proves your lack of understanding the "whole fucking point."

James Reynolds
James Reynolds

Dead fuel accumulating for the past 15+ years. Fires take off like hot cakes. You do the science.

Bobbert
Bobbert

Phd: Early beetle flights resulting in 2 generations per year, instead of 1 is not common knowledge. In fact, it goes against everything we know and accept about the pine beetle. The fact that they can lure a pine beetle with pheromones in May is proof enough. Larvae cannot be lured through the air by pheromones, and pine beetle eggs will not spontaneously grow wings in "cold winter" to be drawn to a trap. The whole fucking point is that weather changes are now allowing 2 generations per year instead of 1. You want to see this test run during the egg stage? Do you see insects cruising around when the weather is cold? Do you really think that beetles trapped using pheromones in May are less developed than the one they happened upon on Niwot Ridge in May? And what would running the experiment with "other beetle types" look like and what would it have to do with proving or disproving the fact that pine beetles are squeezing out 2 generations where they used to make 1?

Nroush
Nroush

Good article about the pine beetle devestation, however the title is misleading. The subtitle additionally says why the forests ate burning up, like there is a correlation between the beetle and all of the current fires. There is only a few sentences that talk about the fires and it never mentions a correlation between the two problems. False advertisement!

Phd
Phd

The article is an example of lacking journalism filled with a lack of citations and filled with conjecture. Worse, the article is stale information. The beetle kill is common knowledge and the simple method of "They set up lures loaded with pheromones to invite beetles to establish broods in those trees." Then stating warm winter sampling represents the first peer-reviewed report of the insect achieving two generations in a single summer. Show this result without luring beetles with pheromones. Then try the same experiment with pine bettles during a cold winter. And finally try the experiment with other beetle types.

Edmund
Edmund

Yea, you're right. He should have written it as "The top ten things you didn't know about pine beetles!" Or maybe 5 in your case.

Ranger
Ranger

Single season multi generations during an upswing in warm winters gets you excited? Read closely, and I see your comment about jerking off - that polishes your stance. Plain, simple, concise and without argument - it’s lack of forest diversity. Now you can once again start your multi seasonal pseudo physical and biased masturbation and please stop writing comments where you have no expertise or degree. Grower, thank you.

 
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