With a couple clicks on his computer, Robert G. Wagner finds the page he’s looking for and cues up a video loop. On a weather map, a huge snowstorm builds, blowing across the St. Lawrence River from Quebec into New Brunswick. Except, it’s not a snowstorm. The weather map shows a scene from July 2013. And that’s an enormous flight of spruce budworm moths.

“It’s astonishing,” said Wagner, a forestry professor at the University of Maine and the director of the Center for Research on Sustainable Forests and the Cooperative Forestry Research Unit. “It turns out that Doppler radar, which we use to show rainfall and snow, can actually pick up [spruce] budworm flights.”

This flight — estimated by the Canadian government at more than 1 trillion moths — took wing two summers ago and fueled by a low-pressure system, flew across the St. Lawrence to Rimouski, Quebec, a town on the south shore. Once there, the budworms took up housekeeping and began doing what they do: The offspring of those moths ate white spruce and balsam fir trees, leaving a dying and defoliated forest in their wake.

“As I understand it, [the spruce budworm moths] can actually sense a low-pressure system coming in, and as the front’s coming in, they take the sail and will catch the wind,” Wagner said. “That’s how they get the mass migrations and they can populate food sources in other places.”

At the present time, more than 15 million acres of Quebec and New Brunswick woodlands have been killed by spruce budworm, according to Wagner. It takes several years for an infestation to lead to defoliation, but that’s beginning to take place in parts of Atlantic Canada.

From the Bangor Daily News: http://bangordailynews.com/2015/12/10/outdoors/its-coming-maine-readies-for-new-battle-with-spruce-budworm/