NEAR SYLVAN LAKE | John Ball is hunting for bug larvae that looks blackened and shriveled like bad bananas.
But after chipping off the bark of Ponderosa pines with a hatchet on Monday in Custer State Park, he wasn’t finding any.
Instead, Ball, an entomologist and tree health specialist for the state Department of Agriculture, held a vial of creamy-white Mountain Pine Beetle larvae. It is the color of bug spawn that likely survived a December cold snap that featured several days of below zero weather.
Even as the mountain pine beetle epidemic that started in 1997 appears to be waning, some hoped the deep freeze earlier this month would speed along the decline.
That, however, is apparently not the case, Ball concluded after his inspection.
"My opinion is they came through just fine," said Ball, 60.
This time of year, mountain pine beetles would need to be subjected to temperatures of 35 degrees below zero for three days or perhaps 20 degrees below zero for a week, according to Greg Josten, forest health supervisor with the state Department of Agriculture.
"These insects basically produce a kind of an anti-freeze that helps them survive this cold winter," said Josten.
That's why Ball chose this particular spot to check beetle larvae. Just down from the entrance of the Sylvan Lake Lodge Resort and not even a stone's throw from some cabins, this area has reached temperatures as low as 21 degrees below zero, according to Ball.
But if the specimens Ball is collecting are a solid sample, the beetles survived. Just to be sure, he'll take them to his research space in Brookings and put them in a humidifier for 24 hours. If the larvae survives, the ones in the trees probably did, too.
"If they stay active after 24 hours, they're healthy as can be," said Ball, adding that by December most of the larvae have likely winterized, according to Ball.
Angie Ambourn, an entomologist with the U.S. Forest Service, points to a piece of trunk where the pine beetle has sheared off the bark. Her fingers trace the path under the bark where the parent beetles have burrowed beneath the bark and mated. Branching off are trails where the beetle larvae have moved across, feasting on sugary nutrients that the tree needs to survive.
Ambourn also points to blue stain fungus — it looks exactly how it sounds — that the beetles carry into the tree. It also hurts the tree.
"The beetles and the fungus together actually kill the tree," she said.
Mountain pine beetles have affected more than 400,000 acres of the Black Hills since 1996, according to a report by the Black Hills National Forest.
The beetles worry Ball and Ambourn since dead trees hurt the the visual qualities of the Black Hills, can create fire hazards and hurt the timber industry.
"The loss of these trees means that they're going to go through quite a few years without having a lot to cut," Ball said.
But Ambourn has recently done research suggesting that the pine beetle epidemic, now more than 15 years old, is waning. Her research shows that many tested areas aren't getting worse and some areas are seeing fewer trees killed by beetles.
There are still some parts in the Northern Hills, however, where beetle kills have been going up.
But Ball is optimistic for different reasons.
"We have epidemics every 40 years," he said. "There's going to be trees here when this is over."