Sprinkle-size southern pine beetles are killing Long Island's pine barrens. There's a plan to stop them.

More than a decade after southern pine beetles were first discovered in Long Island’s forests, hundreds of thousands of conifers have died — a sight that has become vivid this spring as deciduous trees leafed out and greened up.

Roughly 5,000 acres of pine barrens, a globally rare ecosystem, have been infested, according to foresters at the state Department of Environmental Conservation, dramatically altering the landscape.

While foresters fear some of the pine forest will be lost for good, they also are finding reasons for guarded optimism. A pilot program started five years ago to thin the pines provides a strategy for slowing the beetles' spread.

"For all the damage it's doing, I think it's finally making people realize that these forests need to be managed," said Kathy Schwager, an ecologist at the Brookhaven National Laboratory in Upton, which is surrounded by pine forest.

The pine beetle crisis demanded better forestry practices, Schwager said, especially targeted thinning and burning, which mimic the natural cycles of wildfire that sustained the pine barrens for hundreds of years. Over time, those efforts should make these ecologically sensitive woodlands "more resilient to the southern pine beetle."

Long Island’s pine barrens — about 50,000 acres of relatively intact pine and mixed pine and oak woodlands — had grown dense after decades of fire suppression. That density, experts say, provided a tempting target for the beetles.

The tiny insects — each about the size of a single chocolate sprinkle, as DEC forester John Wernet described them — feed on the inner bark of pines and the fungi the beetles bring with them, and they use chemical signals called pheromones to call others to a healthy food source. Where trees are closely spaced, the signals are more easily received, bringing reinforcements in such huge numbers that the tree cannot fight the infestation.

In a more open woodland, pheromones disperse and the insects lose their way. Each tree also has fewer near neighbors with which to compete for sunlight, nutrients and rain, leaving them healthier and more able to defend against pests.

Fire policy began to shift by the 1990s, and when the pine beetle started ravaging the area in 2014, state foresters began spot suppression — cutting infested trees — as well as thinning healthy trees to open the canopy and slow the spread. And they began setting prescribed fires to clear some of the dense understory.

A pilot project in Rocky Point woods

On a cool day in late April, Wernet checked a funnel trap strung between two trees on state forest land in Rocky Point. The trap was baited with pheromones, to catch any pine beetles that might find their way to the area. So far they haven’t been spotted in these woodlands.

The DEC has established a demonstration project on this portion of its property, with three test plots of 3 acres each: one where trees were thinned and carefully burned about five years ago; another where trees have been thinned only; and a control plot that has been left untreated.

In the control plot, the pines and oaks were closely spaced, and a thick tangle of shrubs prevented easy walking.

In the plot that has been both thinned and burned, the lower foot or two of the pitch pine trunks were blackened. (The trees are unharmed, as their thick bark evolved to withstand occasional wildfires.) The tangle had been cleared. Young blueberries and huckleberries — classic pine barrens native understory plants — were thriving in the filtered light. And tiny pitch pine seedlings, just a few inches tall, were emerging from the dried leaves and pine needles on the forest floor.

"This is what we’re going for," Wernet said.

Farther east, in the David Sarnoff state forest in Riverhead, the DEC has thinned nearly 600 acres in the same way. And the agency plans to expand its work in Rocky Point. The hope is that these forests will never be as damaged as Napeague State Park, Henrys Hollow state forest and Quogue Wildlife Refuge, on eastern Long Island, where infestations have been especially severe.

The DEC has spent more than $4 million to fight the beetles since 2016, and continues to receive $500,000 a year for those efforts, up to half of which is used for the prescribed fire program in the barrens.

A more open canopy, and new growth in the understory, also improves the habitat for many of the species that live in the pine barrens, including rare ones such as eastern tiger salamanders, spadefoot toads and northern harrier hawks.

At the Brookhaven lab, too, "We’ve been ramping up our forest management work," Schwager said. This year they thinned 66 acres, twice the area they treated last year.

Sometimes the burns cause collateral damage. The work takes place in the winter months, before female northern long-earned bats, an endangered species, begin roosting in trees with their pups. But last year prescribed fires killed about 30 box turtles, a species of concern in New York, according to Jason Smith, the science and stewardship manager at the Central Pine Barrens Commission. 

DEC foresters said last winter’s frigid weather is unlikely to make a significant difference in the beetle populations.

"Unfortunately," Cole said, "most of the temperatures on Long Island, even though it may have been colder than the past few winters, it still wasn't quite cold enough."

More oak forests

For the past decade, Schwager said, "we were in the epidemic phase of southern pine beetle infestation," but that phase may be coming to an end.

Eventually, "if we restore pine barrens the way that they're meant to be, the habitat will be less hospitable," she predicted. The beetles will not be eradicated but the infestations will be smaller and more isolated. "It'll come into balance."

But a generation from now, Long Island’s pine barrens are likely to be greatly altered. In some of the places damaged by the pine beetles, new pitch pine seedlings have sprung up. At Henrys Hollow, Wernet said, some saplings are already 10 feet tall. "We are very excited for that."

Elsewhere, though, such as in the Wertheim National Wildlife Refuge in Shirley — where the beetles were first spotted on Long Island — pitch pine seeds aren’t germinating. "They're just overshadowed by the oak," Wernet said. "There’s very, very little pitch pine regeneration."

Over time, those forests will most likely be dominated by oaks, and some parts of Long Island’s thousand-year heritage of rare pine barrens will disappear.

Newsday's Alek Lewis contributed to this story.