From Yale 360
A new study has found that some populations of mountain pine beetles are producing two generations of tree-killing offspring each year, a phenomenon that may help explain the scale of damage being done to vast tracts of lodgepole and ponderosa pines across western North America.
After observing beetle behavior during the summer months, scientists from the University of Colorado, Boulder, were surprised to see that some beetles that had been hatched just two months earlier were already attacking trees. Typically the mountain pine beetles spend a winter as larvae within the trees before emerging as adults the following summer.
According to the researchers, this extra generation could produce 60 times as many beetles devouring trees in a given year. Since the late-1990s, oubreaks of the mountain pine beetles — linked to warmer winters — have devastated more than 70,000 square miles of forest in western Canada and the U.S., the largest known outbreak in history.
“This thing is immense,” said Jeffry Mitton, a CU-Boulder professor of ecology and evolutionary biology and lead author of the study published in The American Naturalist.