Small Pests, Big Problems: The Global Spread of Bark Beetles

Dead trees in a California forest in August 2016. U.S. Forest Service

First, mountain pine beetles devastated lodgepole and ponderosa pine trees across western North America. Then came spruce beetles, which have targeted high-elevation Engelmann spruce, spreading from New Mexico into Colorado and beyond. Altogether, with their advance fueled by climate change, bark beetles have ravaged 85,000 square miles of forest in the western United States — an area the size of Utah — since 2000. Pine beetles also have killed trees across roughly 65,000 square miles of forest in British Columbia, and in the southeastern U.S., they have caused millions of dollars of damage to the timber industry in states such as Alabama and Mississippi.

The beetles are now advancing up the Atlantic coast, reaching New York’s Long Island in 2014 and Connecticut the following year. A new study projects they could begin moving into the twisting pitch pines of New England and the stately red pines of Canada’s Maritime provinces by decade’s end. Warming winters could push the beetles north into Canada’s boreal forest within 60 years, climate scientists say.

And from Europe to Siberia, bark beetle outbreaks are erupting with increasing frequency in woodlands weakened by rising heat and drought. Switzerland is preparing for the eventual loss of spruce, its most important tree, as warmer weather fans conditions that will make it nearly impossible for all but those high in the Alps to survive. The Czech Republic, Poland, Germany, and Slovakia are all experiencing intense beetle attacks on their Norway spruce. In Siberia, a related spruce beetle has helped another insect pest, the Siberian silk moth, damage more than 1,100 square miles of Siberian fir, pine, and spruce since 2014. That infestation is now spreading northward into historically outbreak-free boreal taiga stands. 09-26-17

Read more at Yale Environment 360