An explosion in the mountain pine beetle population means these tiny insects are invading many more trees than usual, and that’s killing forests.

 

Winter is coming, and in the western Canadian province of British Columbia that means that hungry larvae, or immature beetles, are busily feasting. In recent years, the larvae of the mountain pine beetle (Dendroctonus ponderosae) have chomped their way through huge forests, killing a third of the oldest trees in British Columbia.

 

The current population hatched beneath the bark of pine trees from eggs laid in early summer, and must now eat constantly to grow into adulthood.

 

“We’ve lost the equivalent of 11 million logging trucks worth,” says Rodney DeBoice, coordinator of beetle control efforts for the province.

 

DeBoice says one reason so many trees are dying is that the beetles find it easier to chew into older trees—and more trees are living longer thanks to modern fire prevention.

 

Not only are there more old trees, there are a lot more beetles. A few years ago, colder winters helped control beetle numbers by killing many of them. Warmer winters mean more survivors.

 

“Temperatures need to stay lower than 40 degrees below zero to put a large dent in the population,” explains DeBoice. So a lot more beetles are surviving—and eating.

 

The mountain pine beetle finds shelter and food in the pine trees where it spends most of its life. In early summer females no larger than the head of a match lay tiny eggs that develop into larvae in the fall.

 

The hungry larvae eat away at the tree’s life system through the winter. Once they chew a ring all the way around the tree, water and nutrients can no longer flow throughout the tree and it dies.

 

Experts say by the year 2013, 80 percent of British Columbia’s mature pines will be dead. DeBoice says that isn’t as bad as it sounds: “Keep in mind, we have a lot more young pine forests growing up than we have old pine trees.”

 

 Fast Facts:

• Pine beetles spend all but a few days of their lives sheltered inside the trunks of pine trees.
• In summer, females come out from under the tree bark where they live. They glide on the wind to a new tree, sometimes as far as 12 miles (20 kilometers) away, where they meet with males and lay their eggs.
• Beetle infestation makes the pine needles turn from green to red to gray as the tree dies.
• The mountain pine beetle lives in British Columbia and Alberta, Canada, as well as a dozen states in the United States and in Mexico.