Podcast: Ranchers Stewardship Alliance – Martin Townsend and David Naugle
December 10, 2024
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January 1, 2025Meet the American Burying Beetle, the continent's largest carrion beetle
Thanks to decades of dedicated conservation practices by private agricultural landowners, America's largest carrion beetle is starting to recover on healthy prairies in the Loess Canyons.
Photo: Cindy Maynard, USFWS
Nature’s cleanup crew at work
In the prairie twilight, a giant beetle with a red-orange head emerges from the ground. It flies over wide-open grasslands in search of a dead animal, preferably something the size of a quail.
Once the beetle finds a fresh carcass, it wrestles it back underground to its lair. Next it secretes an embalming fluid from its anus that preserves the dead animal so its babies can feed on it.
It sounds horrifying, but the American burying beetle provides an essential service: they clean up our landscape.
Sadly, populations of North America’s largest carrion beetle have been decimated due to habitat loss and dwindling numbers of the wildlife they feed on. They are listed as threatened under the Endangered Species Act.
New hope for the beetle
The good news: new research shows that American burying beetles are making a comeback in Nebraska’s Loess Canyons. This success story is thanks to decades of voluntary conservation actions by private landowners who have defended core grasslands that the beetles need to survive.
By working to protect the American burying beetle, we also protect many other species that rely on healthy grasslands, including prairie chickens, songbirds, pronghorn, and elk.
Photo: Alex Harman, CC-BY-NC inaturalist.org/photos/47383310
American burying beetles rely on grasslands
American burying beetles were once abundant in 35 states and 3 Canadian provinces. But by 1989, when this insect was listed under the Endangered Species Act, the only known population was in Rhode Island.
Today, people have found or reintroduced these beetles in grasslands in ten states: Nebraska, Kansas, Texas, Oklahoma, Arkansas, Missouri, Rhode Island, Massachusetts, Ohio and South Dakota, as this map from the U.S. Fish and Wildlife Service shows.
“The scale and quality of grassland habitat matters to this beetle as much as it matters to a prairie chicken or a pronghorn.”
A small bug provides a big umbrella
Since they require wide-ranging grassland habitat and prey, the American burying beetle is a flagship indicator for how the biome is faring.
Their numbers plummet when the land is plowed up for crops, subdivided for buildings, or taken over by encroaching trees or invasive species. Even light pollution might put this nocturnal insect at risk.
Luckily, proactive approaches that conserve large and intact grassland core areas are making a difference for the American burying beetle.
Protecting and expanding grassland cores benefits a lot more than just one fascinating insect species—it also helps pronghorn and prairie chickens, grazing livestock and rural communities, and so much more.
Photo: Dillon Fogarty
About the American burying beetle
LIFE CYCLE
FOOD
REPRODUCTION
LIFE CYCLE
American burying beetles live about one year. They are active from late spring through early fall.
Once nighttime air temperatures are above 59°F in the spring, adults emerge from the ground. They fly out in search of a mate and to find carrion to eat.
A pair will locate and bury a carcass, then the female lays eggs beside it. Offspring emerge in the summer.
When the air cools in the fall, they bury themselves in the soil to hibernate over the winter.
These beetles are nocturnal. During the daytime, they bury themselves under vegetation like leaf litter, or under the soil.
FOOD
These large beetles aren’t picky eaters! They are attracted to any kind of vertebrate carcass, including mammals, birds, amphibians or reptiles.
Burying beetles can sense a carcass at least two miles away. The find carrion that has been dead for less than two days.
While the species of prey doesn’t matter, the size does. To feed their young, American burying beetles need a carcass that weighs 3.5 to 7 ounces — about as big as a dove or a quail.
If the carcass is smaller, the females may produce fewer eggs. Plus, parents will cull their larvae through cannibalism if there’s not enough carrion for the whole brood.
Photo: American Burying beetle next to rodent carcass. Cindy Maynard, USFWS
REPRODUCTION
Unlike most insects, both American burying beetle parents participate in caring for their young. First, they find and bury a carcass. Next, they bury the body in 24 hours or less.
Once the carrion is underground, both parents strip off any fur or feathers. Then they roll the carcass into a round lump called a brood ball.
The beetles cover the ball with secretions from their mouth and anus to embalm it. This helps the brood ball last longer for their babies by slowing the growth of mold or bacteria.
The female beetle lays eggs in the soil right next to the carcass, which hatch about six days later. Broods usually total 12 to 18 larvae.
The parents open a small hole in the top of the brood ball, and regurgitate carrion for the larvae to eat. One or both parents remain with the larvae until they reach the next stage of their life cycle as a pupae. The larvae will die without parental care.
The entire reproductive process from carcass burial to the offspring’s emergence as adults takes 30 to 65 days.
Across the Great Plains, perennial prairies face two main threats:
Woodland Expansion
Land-use Conversion
Grassland Conservation in Nebraska
In Nebraska’s Loess Canyons, landowners have successfully reversed tree encroachment to save some of the last, best grasslands on earth. Local groups are leveraging funds and expertise from WLFW’s Great Plains grasslands to perform prescribed burns on hundreds of thousands of acres.
These fires mimic natural processes to rejuvenate the biome, and also keep encroaching redcedars from taking over prime rangelands. Keeping grasslands intact and healthy is good for ranchers, livestock, and wildlife like the American burying beetle.
Photo: Christine Bielski
We are firm believers that what is good for our cows is great for many different species of wildlife, even beetles. It's impressive to see how everything depends on fire to survive.
Beetles Make A Comeback In Nebraska's Loess Canyons
New research shows that keeping grasslands open and healthy benefits beetles. The abundance of American burying beetles in the Loess Canyons increased by 17% from 2007 to 2019. This is the first landscape-level increase for these insects since they were listed in 1989.
Scientists also studied what type of land cover the beetles prefer. They found that once tree cover reaches 10 percent—or just a few trees dotting the prairie—American burying beetle abundance plummets to nearly zero.
Plus, when 0.1% of native grasslands were converted into crops, beetle abundance also dropped significantly. That means plowing up just 14 out of 1,400 acres is bad news for this at-risk insect.
The good news? When perennial grass cover reaches 46% to 80%, beetle populations double!
Defending core grasslands by removing invading trees is the number one action that will do the most good for the American burying beetle.
This science also shows that the best bet for ensuring wildlife species recover and flourish is to carry out conservation strategies at an ecosystem-scale—just like landowners in the Loess Canyons are doing.
Researcher Alison Ludwig found that prescribed fire in the Loess Canyons did not harm beetle populations.
participating ranchers
tree cover pre-burns
tree cover post-burns
increase in American burying beetles
The American burying beetle increase in the Loess Canyons is a ‘comeback kid' story. It's a hopeful reminder that we can restore places and wildlife populations will increase.
Science-backed conservation benefits everyone
Conserving core grasslands aligns with WLFW’s Framework for Conservation Action in the Great Plains Grassland Biome.
Working Lands for Wildlife focuses resources on helping private agricultural landowners keep core grasslands intact. This is more cost-efficient and effective than trying to restore areas that are already heavily infested with trees or re-naturalize areas where rangelands have already been plowed up for crops.
More good news for American burying beetles in the Great Plains
Nebraska’s beetles are helping restore wild populations farther afield. In Ohio, where the American burying beetle was extirpated in 1974, the Columbus Zoo and Aquarium and the Cincinnati Zoo are reintroducing the species. They collected 30 breeding pairs from Nebraska in 2022, which have produced 1,091 offspring. In 2023, 688 American burying beetles were released into the wild in southeast Ohio.
In Missouri, the Saint Louis Zoo WildCare Institute Center for American Burying Beetle Conservation has bred more than 14,000 American burying beetles since 2005. The beetles have been re-introduced to native grasslands in four counties in southwest Missouri.
Annual surveys have found wild-born beetles, too, giving hope that these natural janitors will one day be cleaning up carcasses across America’s prairies.
This is the holy grail of endangered species conservation. These success stories are incredibly rare, especially for tiny species like bugs and especially at a landscape scale.