QUANTICO, Va. (AP) — When the sun sets and nearby Marines wind down for the evening, Sam Freeze suits up and goes bat hunting.

Six nights a week in the summer, the doctoral student at Virginia Tech tromps through the woods at Marine Corps Base Quantico in search of northern long-eared bats — a species decimated by a mysterious disease in recent years. Most nights, the search comes up short.

Between May and August, Freeze might catch fewer than 10 northerns at his arboreal outpost just off Interstate 95. Pseudogymnoascus destructans, a fungus that causes the fatal illness known as white-nose syndrome, has killed more than 90 percent of these bats in some parts of North America, making the nocturnal animal hard to find.

Researchers want to stop the bat apocalypse by locating them and reverse-engineering how they survived. Amid the species devastation, the search for northern long-eared bats in the Washington area can lead to two places where some have survived: Quantico in Virginia and Rock Creek Park in the District.

“We have to understand what we need to protect,” Freeze said.

This is no small undertaking. Searching for northern long-eared bats in a forest near the Marine base requires the cooperation of the U.S. Fish and Wildlife Service, National Park Service, the U.S. Geological Survey, Virginia Tech and Quantico. Bats can echolocate, but they cannot tell when they have entered a military zone or crossed a political jurisdiction.

After the bureaucracy comes the gear. Freeze’s team hangs several “mist nets,” which look like extra-large volleyball nets rising more than a dozen feet in the air. Omnidirectional microphones catch the sound of bats that show up but elude capture.

When a bat flies into the trap, it is placed into a brown paper bag and marched about 100 yards to a folding table, where Freeze has set up an outdoor lab, and the examination begins.

Researchers record the weight and gender of the animals and take fecal samples to determine their diet. The bats are tagged with small transmitters — affixed to their backs with surgical glue at $200 a pop — as they try to bite the hands of scientists trying to help them.

Freeze is prepared for the gnawing of tiny teeth.

“I’m wearing batting gloves, ironically,” he said while handling an eastern red bat — a species in which the fungus that causes white-nose has been found but has not caused illness. Once tagged, the bats are freed and tracked with a device that resembles a Speak & Spell toy attached to an antenna.

Since the winter of 2007-08, millions of bats in 33 states and seven Canadian provinces have died from white-nose syndrome, according to the U.S. Geological Survey.

The effects of deaths in the bat population are not fully known. Bats eat a lot of insects, which means farmers might have to battle uneaten bugs with more pesticides or risk losing more crops. On the other hand, there are many other bats and bug predators, experts say.

“It’s tough to guess if it’s going to have a long-term effect on pest control in agricultural systems,” said Justin Boyles, a professor in the zoology department at Southern Illinois University at Carbondale. “Enough species are around that we may see them pick up the slack.”

Whatever the effect on the economy, there are a lot fewer northerns, a species hit hard by white-nose syndrome.

“I have literally seen this species decline before my very eyes,” said Mark Ford, a Virginia Tech professor affiliated with the U.S. Geological Survey who oversees Freeze’s bat research.

Ford, who has studied northern long-eared bats for two decades, said he remembers a time when he would catch dozens during mist-netting sessions. Those days are done.

White-nose began to strike more than a decade ago, Ford said, originating in Europe and Asia. Eating away at the membranes in their wings, the disease left piles of dead bats marked with telltale white dots in caves where they hibernate. The sickness seems to wake them from their winter slumber earlier, depleting critical fat reserves and causing dehydration. When they leave the caves too soon, they can die from exposure or starvation.

A scientific paper published in the medical journal PLOS Pathogens called the disease “the most devastating epizootic wildlife disease of mammals in history.” The infected animals act erratically during winter hibernation, sometimes emerging from caves — where the fungus easily spreads — during the day, then not returning.

Theories abound on why some bats survive: They might avoid caves, spending the winter in trees, where the white-nose threat is lower because of less-cramped quarters. Or some might be resistant to the disease.

The challenge for researchers is to determine why and where they have survived, and what humans can do to help them along.

“We have to put the bats in the context of the landscape,” Ford said. “We have to conserve or build that environment.”

Freeze said homeowners can take actions to protect bats, such as erecting bat houses where they can sleep. When bats are found in attics, Freeze suggests calling a wildlife specialist instead of killing them.

One can even learn to love bats, he said. Freeze is already there.

“The first time I had a little squirming furry monster in my hand, I was hooked,” he said.

Even the Marines are ready to fight for the northern long-eared bat. Quantico spokesman Ken Kunze said that is part of the mission.

“Even though we’re walled away firing weapons and blowing stuff up, we want to protect and understand what’s around us,” he said.