The St. Louis Zoo is working to save a beetle that needs dead animals to survive

The couple moving the body has only the moon to light their way.

And this is no mere cover-up.

“They put this body in this underground bunker they built,” Bob Merz said. Once there, they roll it into a ball and coat it in preservatives.

They then cut off pieces of meat to feed to their children.

Luckily, no one in this story is human. They are American burying beetles and their actions are bad but important, said Merz, deputy director of the St. Louis Zoo's WildCare Institute.

By transporting the dead bodies of small birds and rodents underground, the beetles perform an important cleanup for wildlife. But their numbers have declined sharply.

These special insects were once found in 35 states, but the U.S. Fish and Wildlife Service now considers them federally threatened.

While trick-or-treaters prepare their Halloween costumes, Merz and his colleagues at the St. Louis Zoo work to stage a comeback for the spooky American burying beetle.

Sophie Proe

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St. Louis Public Radio

A macabre insect

In a closet-sized quarantine room at the St. Louis Zoo hidden from the public, more than 100 burying beetles hide in crumpled paper towels in individual clear containers. The black insects, up to one and a half centimeters long, have bright orange spots on their backs.

This is the zoo Center for American Burrowing 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 sure we just had to look for it,” Merz recalled.

After more than 10,000 nights of trapping across the state, surveyors still hadn't found a beetle. The last known sighting in Missouri was in the 1970s.

“Then we realized that a more intensive effort was required,” said Merz.

Twenty years later, the zoo has bred more than 14,000 American burying beetles in captivity. Center staff also reintroduce them to specially selected locations in southwest Missouri and monitor their numbers in the wild.

To get to this point, the zookeeper had to do a lot of matchmaking, using computer software to find beetles that are genetically diverse.

To breed the insects, zookeepers place a potential pair of beetles and a dead quail in an orange bucket with a net on top. When the beetles become romantically interested in each other, they begin processing the carcass by removing feathers and fur and shaping the carcass into the shape of a meatball using preservative secretions. Next, the female lays eggs.

“Once those eggs hatch into the little larvae, (mom and dad beetles) actually take care of their babies,” said Kayla Garcia, the zoological invertebrate manager. “That’s really, really rare in the insect world.”

The beetles make small beeping noises to communicate with each other while the parents regurgitate food for their larvae, “just like a mother bird feeds her babies,” Garcia added.

In the summer, the zoo releases beetles in the hope that they like their new home. Then the surveyors check the beetles to see how they are doing. Zookeeper Rebecca Gann spent a summer in southwest Missouri with the zoo's conservation team searching for the beetles.

The surveyors attract digging beetles by placing rotting chicken parts in mason jars, which Gann says is “smelly.” Very smelly.”

“But it's also exciting because when you see one of these guys trapped, you celebrate a little bit,” Gann said.

There have been ups and downs in the zoo's efforts to protect this insect. At the first location where they were introduced, the population was not doing so well.

“We expected that number to go down without providing all the food and things for them,” Merz said. “But we didn’t expect it to go to zero.”

In the wild across the country, the beetles are apparently struggling to find the right conditions to reproduce, but scientists aren't entirely sure why.

The beetles fared better at a second location in Missouri near the first. But the zoo keeps a captive population just in case.

Sophie Proe

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St. Louis Public Radio

A Goldilocks beetle

The American burying beetle is a “very difficult” species to protect, said Wyatt Hoback, a professor of entomology at Oklahoma State University.

“I've been working on this beetle for 26 years and sometimes it feels like I'm a bad scientist because there are still a lot of things 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 several theories as to why beetle numbers have declined, and scientists believe a combination of ecological factors is putting pressure on the beetle. These include loss of habitat due to farmland, declining populations of the animals whose carcasses the beetle uses to feed its young, and even light pollution, which could affect the insect's nocturnal habits.

The beetle also once lived in roughly the same areas as the American passenger pigeon, which would have been the right size for burial but went extinct in the early 1900s, Hoback said.

The decline is a sign of larger environmental problems, said Merz. He describes them as Goldilocks beetles.

“The Goldilocks beetles are the ones that will tell us when environmental stress is affecting them,” Merz said. “If the beetle cannot thrive, all is not right in the world and in our environment.”

By working to protect the picky burying beetle, Hoback said, people will also protect all other creatures that rely on the same habitat.

“They're very diverse and require carcasses, so it's really difficult to specifically manage them,” Hoback said.

Hoback said the good news is that it is an “umbrella species” because its protection indirectly protects many other plants and animals.

Merz said one of the best things people can do is plant native plants to support the birds and small rodents that American burying beetles need to raise their next generation.

“All of this is not without hope,” said Merz.

This story was produced by St. Louis Public Radio. Distributed by Harvest Public Media.