The Pine Beetle's Deadly March

Wendy Stueck of The Globe and Mail write about the swathe of destruction through British Columbia by the mountain pine beetle:

At night, you can hear them moving in the trees.

They've swept through parks and golf courses and ranchland and caught thermal currents to fly on the jet stream. They've colonized an area 1,200 kilometres long and 575 kilometres wide, nearly the size of Sweden. They're about the same size as a grain of rice but can kill a tree 10 storeys high.

And perhaps scariest of all, they're stealthy. One day, a tree looks fine. The next, it's been hit by nature's version of a drive-by shooting, left with tiny drifts of sawdust at its base or looking as though it's been pelted by popcorn because "pitch tubes" — blobs of sap that are the tree's natural defence — have sprung up on its bark.

Among the causes: climate change. The Globe continues:

Warmer winters meant fewer stretches of -30 C weather, the kind that curtailed previous outbreaks. Recent droughts left trees more vulnerable to attack. And decades of successful fire-fighting — much of it undertaken to protect stands of commercial lumber now threatened by the beetle — left forests overstocked with the big, older trees.

During this decade, the infestation has swept from valley floors to hillsides and beyond. Beetle populations have spiralled. During an aerial survey this past July, provincial bark beetle co-ordinator Rod DeBoice rode in a helicopter that was forced to land because the pilot couldn't see through the mess of beetles splattering against his windshield.

As the outbreak spread, the beetle ate itself out of its traditional habitat and into new ones.

"Five years ago, if somebody had said the mountain pine beetle would kill a 25-year-old stand of pine that's three inches across, you would go, 'you're talking nonsense, that's never been seen,'" Mr. DeBoice says.

"Well, they are doing that now, quite effectively — because it's warmed up enough, in winter they can get under that thin bark and make a go of it and not freeze." ::Globe and Mail

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