How much is a bat worth? Protecting these tiny insect‑eaters isn’t just good for farms – their deaths cost taxpayers and the wider economy
Dale Manning, University of Tennessee; Anya Nakhmurina, Yale University, and Eli Fenichel, Yale University
Most Americans tend to think about bats only around Halloween, but the U.S. economy benefits from these furry flying mammals every day.
Bats pollinate plants, including many important food crops, when they stop by flowers to drink nectar. Their guano is mined from caves for fertilizer. And they eat a lot of bugs – the kinds that bother people (think mosquitoes) and others that destroy crops that humans depend on for food.
Sadly, bat populations are declining rapidly in North America. A driving force is a fungal disease known as white-nose syndrome, which has spread among bats throughout the United States. When a bat population crashes, fewer bats are around to eat bothersome insects. All those additional insects can do serious damage.
So, when bats disappear, farms become less productive, and that has broad implications for the agricultural economy, human health, rural governments and even financial markets.
Bats love to eat the bugs that bother people
First, consider how many insects bats eat.
A reproductive female big brown bat can eat its body weight in insects every night in the summer, precisely when farmers are growing food.
One of those insects is the cucumber beetle, which matures from rootworm – a scourge of U.S. cornfields. Rootworm destroys more than 340 million bushels of corn across the U.S. Midwest and South each year, even as farmers spend US$1 billion annually on pesticides to control outbreaks.
A colony of 150 big brown bats can consume 600,000 cucumber beetles in a single year. If each female cucumber beetle – assuming half are female – had 110 rootworm larvae, the typical brown bat colony would prevent the production of 33 million rootworms.
Farmers experience economic damage when rootworm concentrations exceed about 0.5 per corn plant. Typical planting densities exceed 30,000 corn plants per acre in the Midwest. Therefore, the rootworms that would have hatched could damage more than 2,000 acres of corn – if bats weren’t around to eat the cucumber beetles first.
That is a significant amount of pest control provided by bats!
The disaster known as white-nose syndrome
In the winter of 2006, the fungus that causes white-nose syndrome, the aptly named Pseudogymnoascus destructans, was first detected in the U.S. near Albany, New York.
From there, it spread across the country, infecting 12 species of bats, three of which are listed as endangered under the Endangered Species Act. A 2010 study found white-nose syndrome had killed between 30% and 99% of the bats in infected colonies.
As of March 2026, the fungus causing white-nose syndrome had been detected in 47 states, reaching as far west as California, Washington and Oregon. White-nose syndrome spreads primarily through bat-to-bat contact, though humans also contribute to the spread when cave explorers carry the fungus from one cave to another.
Despite coordinated efforts by state and federal wildlife agencies to limit access to caves where bats live and slow the transmission, white-nose syndrome continues to spread rapidly. When bats get infected, they wake up early from hibernation and use more energy over the winter. This depletes their fat reserves and causes them to die of starvation, leading to plummeting populations.
Bats’ role in food production
After white-nose syndrome arrives in an area, the loss of bats has significant consequences for farmers.
Yields fall as pests consume crops. To protect their crops, farmers purchase more chemical pesticides, so their costs rise as yields decline. The estimated agricultural losses from white-nose syndrome exceeded $420 million per year as of 2017.
Greater pesticide use is also associated with human health problems that can be avoided if bat populations remain healthy.
Losing bats hurts local governments financially
The story does not stop at the farm.
Counties in all U.S. states tax agricultural land based on its “use value” – in other words, based on how profitable the land is in agriculture. Without healthy bat populations, lower profits shrink the tax base, leaving county governments with less revenue.
Those governments must respond by reducing services, raising taxes or increasing how much money they borrow – often at a greater cost of borrowing. The effect is especially pronounced in rural counties, where agriculture makes up a large share of property tax revenue.
Our recent research finds that rural county governments lost almost $150 per person in annual revenue after the arrival of white-nose syndrome. For an average-size rural county, that is nearly $2.7 million in lost revenue each year.
How losing bats can hit the bond markets
The loss of county revenue makes municipal bond investors nervous. Buying a municipal bond is a bit like lending money to the county, and the interest rate is what the county pays you for taking on that risk.
When bats disappear, the risk goes up, and the county has to pay about 11.47 hundredths of a percentage point more in interest. That may sound small, but it is 27% larger than the typical risk premium investors already demand from county governments.
The higher interest rate raises borrowing costs for county governments. For example, the borrowing costs on a typical 15-year, $1 million bond would increase by more than $33,000.
Higher yields also mean lower bond prices for investors, including retirement funds. For example, our research suggests that investors would discount a $1 million bond issued by a rural county by nearly $14,000 if that county’s bats have become infected by white-nose syndrome.
Economic benefits of saving bats
The good news is that the benefits from healthy bat populations create opportunities to make money from bat conservation.
Farmers can increase their incomes. Local governments can recover property tax revenue to fund public services, such as road maintenance, health infrastructure and public schools. Bond investors can earn financial returns from healthier bat populations.
No silver bullet exists for protecting or restoring bat populations affected by white-nose syndrome, but promising efforts are underway.
A fungal vaccine is being tested by the U.S. Geological Survey and partners. Designing artificial roosts and adding cave protections can also help preserve healthy bat populations. Researchers are also working to better understand bat resistance to the disease to explore whether improving resistance alone can stabilize bat populations.
As these solutions develop, opportunities will emerge for farmers, local governments and investors to earn financial returns through bat conservation. In other words, saving bats isn’t just good ecology – it’s good economics.
Dale Manning, Associate Professor in Public Policy and Agricultural and Resource Economics, University of Tennessee; Anya Nakhmurina, Associate Professor of Accounting, Yale University, and Eli Fenichel, Professor of Natural Resource Economics, Yale University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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