On a clear September night along the San Marcos River in central Texas, a handful of people in headlamps gathered around a small, noisy creature: an evening bat.
Melissa Donnelly, a science specialist with the nonprofit Merlin Tuttle’s Bat Conservation, delicately measured its wing. She caught the chattering bat over the river in a supersized tennis net.
“This is very typical of the species,” Donnelly said, as she held the bat that’s no bigger than a clementine. “They’ve got a lot to say all the time.”
The tiny brown bat is one of millions who fill the Texas skies each night, and collectively eat tons of insects. They’re essential for farms – including where the researchers are working: Swift River Pecans.
The orchard’s owner, Troy Swift, hosted the researchers so they could collect more information on the species that visit his 266-acre property, and to show off the bats’ value to his operation.
The researchers have been working to prove that the bats are eating pests that destroy pecans in Swift’s orchard, like the pecan nut casebearer moth. The team collects samples of bat guano and sends it off to a lab for DNA analysis.
“Really, what we’re trying to do is figure out what agricultural pests they’re eating,” Swift said. “And we have found they eat a lot of them.”
Embracing bats for pest control is part of a broader effort by Swift to produce better pecans by improving the health of his trees and soil. And he’s hoping other farmers follow his example.
“Our job is to work with Mother Nature instead of against her to make the best pecans money can buy. That’s the way we see it,” Swift said.
Building better bat boxes
Swift didn’t always take this more organic approach. When he first bought his orchard in 1998, he protected his trees the way many farmers do: with plenty of chemicals.
That started to change after Swift met Merlin Tuttle in 2004. He first knew Tuttle as a guy who he let fish on his property.
“But then I found out he was a famous bat scientist,” Swift said.
Tuttle is an ecologist and conservationist who has spent 65 years studying bats around the globe, including at Swift’s orchard. Tuttle said you’d be hard-pressed to find better bat habitat.
“If your orchard is near a river, you have a very good opportunity for attracting bats to bat houses,” Tuttle said.
Tuttle has also been using Swift’s orchard to experiment with bat boxes – tweaking the color, position and even what kind of wood they’re made with. Swift runs a sawmill at his orchard where he makes lumber out of punky cypress trees. Turns out it’s perfect for bat houses.
“It’s extra lightweight, extra insulative, and yet it’s one of the longest-lasting woods in America,” Tuttle said.
The cypress wood is porous on the inside, which gives the bats something to hold onto in the house. It also regulates temperature well, which is crucial for bats in hot places.
“What we’re doing is actually helping,” Tuttle said. “We’re not just giving the bats that were already there a place to live. We’re building populations with more bats than there were previously.”
More than half of North America’s bats could be at risk of extinction within 15 years, according to a 2023 study by Bat Conservation International and the North American Bat Conservation Alliance. Climate change, habitat destruction, and a deadly fungal disease called white-nose syndrome are all to blame.
Replacing chemicals
There are dozens of bat boxes on Swift’s property, housing hundreds of bats. So many, in fact, Swift decided to forego using pesticides on part of his pecan orchard and just let the bat population handle the bugs this year.
“This year is the first year I did not spray any insecticide at all,” Swift said. “And guess what? We got a really good crop over there.”
Reducing reliance on insecticides is one of Swift’s big goals, he said, because of how they can harm ecosystems, human health and a farmer’s bottom line.
A study published by the journal Science in 2024 found that in counties where bat populations had declined due to white-nose syndrome, farmers responded by increasing their pesticide use – which was associated with higher infant mortality and lower farm revenue.
“There’s a lot of big unknowns [with bats], but I think we know enough to say they’re really important predators and they’re undoubtedly impacting ecosystems as a whole,” said Russ Benedict, a biology professor at Central College in Iowa who studies bats and agriculture.
Using bats to control crop pests may not be a good fit for every farm, though. Bats need diversity in their diet, Benedict said, and they can’t get it from a landscape that’s just acres and acres of the same crop. They don’t thrive in wide-open areas, either.
“Primarily I hear those [bat pest control methods] in smaller operations, folks who are doing organic farming, that kind of stuff,” Benedict said. “Among the corn and soybean folks, I haven’t really heard that much. ”
But for farms where bats could make a difference, Swift said he’s ready to share what he’s learned. As the president of the Texas Pecan Growers Association, he has a platform to inform other farmers about how bats have helped his crops.
“I really want to have an impact on agriculture, not just pecans,” Swift said. “Bats eat stink bugs and corn earworms. So that’s good for all agriculture. And when you talk about mosquitoes and flies, that’s good for people.”
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest and Great Plains. It reports on food systems, agriculture and rural issues.
