INFESTATION UPDATE

A mountain pine beetle is tiny enough to fit in the palm of your hand, yet it can wreak havoc on entire forests. (Photo: WBUR/flickr)

Unbeatable beetles

Beetles are tiny, destructive, and a natural part of a forest’s growth

The way humans deal with endemic beetle attacks in conifer forests hasn’t changed for centuries. To save lumber, we remove infected stands and other valuable trees from the insect’s path. Trouble is, events like the current mountain pine beetle (MPB) outbreak in Western Canada are, like other forces of nature, unstoppable. Climate change, fire suppression and homogeneous planting have aggravated modern outbreaks, but ultimately, infestations are the ecosystem’s cyclical way of regenerating old growth.

The MPB’s range sprawls from northern Mexico to northwestern B.C., and from the Pacific to South Dakota, where a half-dozen tree species are under attack. B.C.’s uniform stands of lodgepole pine have suffered the most losses (17.5 million hectares, an area larger than Florida), but only the massive scale and intensity of the current infestation are unprecedented.

By the late 18th century, as Andrew Nikiforuk writes in Empire of the Beetle (see book review), the European spruce bark beetle “highlighted imbalances in the continent’s impoverished forests” after vast medieval pillaging for shelter, fuel and charcoal had depleted diversity. On Alaska’s Kenai Peninsula, two centuries of recurring infestations preceded the annihilation of 200 million spruce between the late 1980s and early 2000s.

In 20th-century Canada, MPB outbreaks began in 1910 in B.C.’s Okanagan Valley; in the 1930s, the bug killed 90 percent of the lodgepole and ponderosa pines in two 6,500-hectare areas in north-central B.C. and the Rockies. More infestations peppered the province over the next five decades, finally collapsing during two cold winters in the late 1980s. By the mid-1990s, the invasion redoubled ferociously and now resembles a flooded red lung on Natural Resources Canada maps, still hemorrhaging toward Saskatchewan and the boreal forest’s Jack pines.