"Climate change could be throwing common tree killers called mountain pine beetles into a reproductive frenzy. A new study suggests that some beetles living in Colorado, which normally reproduce just once annually, now churn out an extra generation of new bugs each year. And that could further devastate the region’s forests.
Pine beetles (Dendroctonus ponderosae), which scuttle from New Mexico north into Canada, are trouble for trees, says study co-author Jeffry Mitton, an evolutionary geneticist at the University of Colorado, Boulder. Beginning in late summer along high altitude sites in the eastern Colorado Rocky Mountains, for instance, swarms of hundreds or even thousands of these small black bugs will single out individual lodgepole pines (Pinus contorta) or related trees, then advance on them en masse. Females dig deep burrows inside the pines’ trunks and drop down their eggs. They also deposit a special type of fungus that the insects carry with them that grow inside the trees, eventually helping to kill them. Beetle larvae feed on that same fungus throughout the winter, escaping their burrows the following August.
Recently, pine beetles have inexplicably exploded across their range. In British Canada alone, the insects gutted and killed about 13 million hectares of trees in about a decade. Mitton says it’s possible to fly in a small plane over pine forests here for an hour or more and see almost no living pine trees.”