American burying beetles bring dead animals underground, turn them into preserved meatballs and feed them to their babies. The St. Louis Zoo is working to save the threatened beetle.
The couple moving the body only have the moon to light their way. And this isn’t a mere coverup.
“They’re taking this body into this underground bunker that they made,” said Bob Merz. Once in there, they’ll roll it into a ball and cover it in preservatives.
Then, they’ll cut off pieces of flesh to feed to their kids.
Thankfully, no one in this story is human. They are American burying beetles, and their actions are gnarly but important, said Merz, who is the assistant director of the St. Louis Zoo’s WildCare Institute.
By moving the dead bodies of small birds and rodents underground, the beetles perform an essential cleanup for the animal world. But their numbers have plummeted.
These special insects were once found in 35 states, but the U.S. Fish and Wildlife Service now considers them federally threatened.
As trick-or-treaters prepare their Halloween costumes, Merz and his colleagues at the St. Louis Zoo are working to stage a comeback for the spooky American burying beetle.
A macabre insect
In a closet-sized quarantine room at the St. Louis Zoo, hidden away from the public, there are more than 100 burying beetles hiding away in scrunched up paper towels inside see-through, individual containers. The inch- to inch-and-a-half-long black insects have bright orange splotches on their backs.
This is the zoo’s Center for American Burying Beetle Conservation.
When the American burying beetle was listed as endangered in 1989, the only known population was in Rhode Island. Eventually, surveyors found small groups in Arkansas, Kansas, Nebraska and Oklahoma. The zoo tried to do the same in Missouri.
“We were positive that all we had to do was look for it,” Merz remembered.
After more than 10,000 trap nights across the state, surveyors still hadn’t found a beetle. The last known sighting in Missouri was in the 1970s.
“Then we started to realize that a more intensive effort needed to take place,” Merz said.
Twenty years later, the zoo has bred more than 14,000 American burying beetles in captivity. Center staff are also reintroducing them to specially selected sites in southwest Missouri and surveying their numbers in the wild.
Getting to this point meant a lot of matchmaking on the zookeeper’s part, using computer software to match beetles that are genetically diverse.
To breed the insects, keepers place a potential beetle couple and a dead quail in an orange bucket with a net on top. If the beetles are romantically interested in each other, they begin to process the carcass, removing feathers and fur and using preserving secretions to mold the carcass into the shape of a meatball. Next the female lays eggs.
“Once those eggs hatch into the little grubs, [both Mom and Dad beetle] actually take care of their babies,” said Kayla Garcia, the zoological manager of invertebrates. “This is really, really rare in the insect world.”
The beetles make little peeping noises at each other to communicate as the parents regurgitate food for their grubs, “kind of like [how] a mama bird feeds their babies,” Garcia added.
During the summers, the zoo releases beetles, hoping they’ll take a liking to their new home. Then, surveyors check in on the beetles to see how they’re doing. Zookeeper Rebecca Gann spent a summer in southwest Missouri with the zoo’s field conservation team looking for the beetles.
The surveyors attract burying beetles by putting out rotting chicken parts in pickle jars, which Gann said is “stinky. Very stink.”
“But it’s exciting too because when you see one of these guys in the trap you kind of celebrate a little bit,” Gann said.
There have been ups and downs in the zoo’s effort to conserve this insect. At the first site where they were introduced, the population didn’t do so well.
“We expected that number to drop without giving them all the food and providing things for them,” Merz said. “But we didn’t expect it to drop to zero.”
In the wild across the country, the beetles clearly struggle to find the right conditions for reproduction, but scientists aren’t exactly sure why.
The beetles have done better at a second Missouri site near the first. But the zoo keeps a population in captivity, just in case.
A Goldilocks beetle
The American burying beetle is a “very challenging” species to conserve, said Wyatt Hoback, a professor of entomology at Oklahoma State University.
“I’ve worked on this beetle for 26 years, and I feel like I’m a bad scientist sometimes, because there’s still a ton that we don’t know,” Hoback said.
Hoback’s research focuses on how the beetle responds to temperature changes, which could help scientists understand how climate change might affect them.
There are multiple theories about why the beetle’s numbers have plummeted, and scientists think a combination of ecological factors are putting pressure on the beetle. Those include loss of habitat to farmland, declining populations of the animals whose carcasses the beetle uses to feed its young and even light pollution, which could be affecting the insect’s nocturnal habits.
The beetle also used to live in roughly the same areas as the American Passenger Pigeon, which would’ve been the right size for its burying but went extinct in the early 1900’s, Hoback said.
The decline is a sign of bigger problems in the environment, according to Merz. He describes them as Goldilocks beetles.
“The Goldilocks beetles are the ones that are going to be telling us when there are environmental pressures that are impacting them,” Merz said. “So all is not right in the world, all is not right in our environment, if the beetle can’t thrive.”
By working to protect the finicky American burying beetle, Hoback said humans will also protect all of the other living things that rely on the same habitat.
“They’re wide ranging, and they need carcasses, so it’s really hard to manage specifically for them,” Hoback said.
Hoback said the good news is they’re an “umbrella species,” because protecting them also indirectly protects a lot of other plants and animals.
Merz said one of the best things people can do is plant native plants, which supports the birds and small rodents the American burying beetles need to raise their next generation.
“All of this isn’t without hope,” Merz said.