Reproduction was the problem with the first beetle, the Laricobius nigrinus.
“It’s a numbers game,” Salom said. “We can’t produce the numbers we like because they’re a very hard insect to rear.”
While excited by the new beetle, scientists say managing the hemlock-eating pest will likely take a multipronged approach, including chemicals.
Scientists are intent on combatting the adelgids because hemlocks are important ecologically. While hemlocks are cut and milled in New England for siding, in the South they are primarily valued for their ecological role.
Their shade cools streams to a temperature that sustains native trout, and they provide shelter for birds that migrate north to nest, such as warblers.
The adelgid has also taken its toll on history.
It killed the old-growth hemlocks at Rapidan Camp that stood when President Herbert Hoover sought relief from Washington’s heat during the summer months in the Virginia woods. The hemlocks cooled the waters where Hoover fished for trout.
Rhea is cautious when he assesses the latest tack in the fight against the hemlock’s killer, not venturing a guess on how many can be saved. But the alternative isn’t an option.
“If there’s no intervention, they don’t survive very well at all,” he said. “We’ve still lost a lot of hemlocks.”