Celebrating Deep Freeze, Insect Experts See a Chance to Kill Off Invasive Species [View all]

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http://www.nytimes.com/2014/01/09/nyregion/experts-cheer-the-deep-freeze-as-a-killer-of-invasive-insects.html?ref=earth&_r=1


The branch of a hemlock at the Brooklyn Botanic Garden shows damage done by the hemlock woolly adelgid, an invasive species. Nicole Bengiveno/The New York Times

While some people were cursing a canceled flight or wishing they had donned an extra layer on Tuesday, when temperatures in the region took a deep dive, entomologists, foresters and naturalists were rooting for the mercury to drop even lower. That is because the extreme cold has the potential to beat back some of the invasive insects threatening treasured local tree and plant species.

“You do think, ‘Oh great, maybe some of those nasty insects are going to get zapped today,’ ” said Mark Fisher, director of conservatories and horticultural programs at Brooklyn Botanic Garden. “It’s Mother Nature’s way of dealing with this issue.”

The insects, whether introduced pests like the hemlock woolly adelgid or native ones like the southern pine beetle, have weakened forests from Cape May, N.J., to Litchfield County in Connecticut. They are uncannily adept at surviving the winter, but most have a breaking point. And this week, that point was nigh.

“The lethal temperature for the woolly adelgid is minus 4 or 5 degrees Fahrenheit,” said Richard S. Cowles, a scientist with the Connecticut Agricultural Experiment Station, a state research center. “I was cheering a couple of days ago because most of the adelgids will be dying from the temperatures we saw.”