Surprising discovery shows destructive southern pine beetle marching north into NH

  • Close up image of one of the southern pine beetles found in Maine and New Hampshire by researchers at the University of New Hampshire. (UNH - Caroline Kanaskie) UNH - Caroline Kanaskie

  • Researcher Caroline Kanaskie photographs herself holding a cross-section of log damaged by pine beetles in Long Island, N.Y., in 2018. Pine beetles have been found in traps in New Hampshire, but similar damage has not made it to the state. (UNH - Caroline Kanaskie) UNH — Caroline Kanaskie

  • Caroline Kanaskie, UNH doctoral student, holds a specialized funnel trap baited with chemical lures, including bark beetle pheromones, where the southern pine beetles were found in Waterboro, Maine. (UNH - Caroline Kanaskie)

Valley News Staff Writer
Published: 1/20/2022 6:15:13 AM
Modified: 1/21/2022 6:30:06 AM

The southern pine beetle, a destructive pest that can wreak havoc on tree populations if left unchecked, was lured into traps in New Hampshire and Maine, far north of its historical range.

“We were pretty astonished. It should not be this far north,” said Jeff Garnas, a professor of forest ecosystem health at the University of New Hampshire, whose research team made the discovery. “But as the climate continues to change, New Hampshire forests will become viable habitats.”

Cold temperatures set the northern boundary of the beetle, whose stronghold is in the Southeast, he said. The flying insects, which are smaller than a grain of rice, bore under the bark of hard pines where icy air temperatures can kill the beetles. But as the climate warms, the coldest nights are a little warmer than they used to be during some winters, and more of the beetles survive farther north.

“We’ve been detecting a growing trickle of them,” Garnas said. “The populations are moving north. They are around. … Currently the risk is low, but it forewarns that it may become a major pest around here,” he added.

The beetle’s historical range reaches into the New Jersey pitch pine barrens. Its northern range is creeping north, with new infestations in Long Island, Garnas said. The beetles have also been found in new territory stretching from upstate New York to Rhode Island.

Caroline Kanaskie, a Ph.D. student at the University of New Hampshire, found the beetles in cylindrical traps she had hung in pines in Ossipee, N.H. No trap yielded more than about 20 beetles, a small number for a species that uses an army of thousands to kill one tree. There may be a small endemic population subsisting on weak or dying trees, or the beetles may have flown to New Hampshire from farther south, she said.

And although a few robust beetles may have survived this far north, she emphasized that that does not mean New Hampshire’s pines are yet at risk. New Hampshire’s winter nights are still so cold that they would kill off most beetles.

“We’re still in this low-level monitoring stage,” Kanaskie said.

Looking ahead, she hopes to investigate whether the beetles that make it this far north are as robust as their southern counterparts.

The beetles target hard pines, such as red pines and pitch pines. New Hampshire’s coastal pitch pine barrens harbor the vivid, white-bordered Karner blue butterfly, an endangered species, and that habitat would be in danger with the beetle’s arrival, Kanaskie said.

Red pines are scattered in back lots across the state and would likely suffer should the southern pine beetle arrive in force, Garnas said. In the 1930s, the Civilian Conservation Corps planted the fast-growing and easy-to-plant pines across the country.

The beetles tend to shy away from soft pines, including white pines, a culturally and economically important species that is widespread in New Hampshire. But an established population of southern pine beetles would still be a risk to hard pines, Garnas and Kanaskie said.

In the American South, an expensive but effective management system keeps the southern pine beetle at bay, Garnas said. A profitable logging industry pays for a network of pheromone traps to lure the beetles and measure their population — they are most dangerous in “high, high numbers,” he said. Aerial surveillance flags nascent outbreaks as the first infected trees show illness, and then teams with chain saws isolate the infection, cut around it and the beetles disperse.

“It’s labor-intensive,” Garnas said. “The reason it’s financially viable is because in these parts of the country there are still local mills. Here in New England, we don’t really have access to those mills, although we still have some mills that would process the wood.”

But “a well-established paradigm of forest management” will help New Hampshire manage any new pests, said Kyle Lombard, a forest health specialist at the New Hampshire Division of Forests and Lands. “Stands that do very well against southern pine beetles are thinned out, standing well,” he added.

He also raised the possibility that the beetles did not arrive because of a changing climate: Perhaps infested materials carried them north, or the beetles adapted to colder temperatures, or some beetles always traveled this far north but were found now because trapping only began in recent years.

And the red pine scale, an invasive insect, is already killing off the red pine, whose infected branches fester with white blisters.

“It wiped out red pine from New York to Massachusetts,” he said. “The spread slowed down in the ’80s and ’90s, but it finally crept into New Hampshire.”

Claire Potter is a Report for America corps member. She can be reached at or 603-727-3242.

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