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St. Louis Zoo helps save endangered beetles

A female American burying beetle.
(Photo: Dan Kirk)
A female American burying beetle.

By Véronique LaCapra, St. Louis Public Radio


St. Louis, MO – The American burying beetle is one of nature's most efficient scavengers, breaking down dead animals and recycling their nutrients back into the environment.

It's also critically endangered, with only a few small populations left in a handful of states.

A nationwide effort is underway to try to save this unusual insect - including work by a group of dedicated supporters, right here in St. Louis.

On a dark summer night, a couple finds a dead body in a field. They remove the bones, and bury it. Later, they will use the remains to feed their young.

It may sound like a bizarre horror story, but it's just business as usual for Nicrophorus americanus, the American burying beetle.

Nature's recyclers

Bob Merz of the St. Louis Zoo is one of the beetle's biggest fans. He says these thumb-sized, black, red and orange insects can fly several miles in a single night, looking for a small dead animal or bird. When they find one, they fight over it. The winning male and female claim the body, and move it to a safer place.

"And how they move it is they will lay on their backs underneath the carcass and use their legs to push it kind of over them," Merz says. "And so they create this little conveyor belt basically of 12 little beetle legs that kind of move the carcass to a site."

There, the beetles dig a hole under the body, concealing it in the subterranean chamber. They remove the animal's bones, hair, feathers, or fur, and spray the carcass with preservative secretions, forming a kind of gooey meatball.

Then the beetles mate. The female lays her eggs on or near the carcass, and in just two or three days, they hatch.

"This is where it gets kind of cool," says Merz. The beetles will stay with their young and raise them."

When it's feeding time, the adults make a noise by rubbing their flight wings against their hard upper shell. The noise attracts the white, caterpillar-like larvae, who sit up and beg for food - something like baby birds. "And they are cute," laughs Merz. "For a beetle grub, they are cute, they really are."

The search for a disappearing species

A hundred years ago, the American burying beetle was common across North America. Today, it's found in less than ten percent of its historic range. No one knows for sure what happened to the beetles. Theories include pesticides, light pollution, lack of food and the most likely culprit: habitat loss and fragmentation.

Bob Merz and his team from the St. Louis Zoo have been looking for the beetle in Missouri since 2004. Every year, they set out pitfall traps: two-and-a-half quart plastic buckets buried in the soil, with pieces of slightly rotten chicken for bait.

Dan Koch works on beetle recovery efforts for the zoo. He says on a windless day, when he's slogging through a prairie of dense grass that's well over his head, checking the traps can be a pretty smelly business. "The maggots still get in there and lay eggs, and you'll have chicken that really is just a goo of maggots, it's not even chicken anymore by the time you pull up the traps."

Reintroduction efforts

The field surveys have turned up plenty of those fly maggots and other insects - but no American burying beetles. But Merz and Koch have successfully raised more than 5,000 of them at the zoo.

Retired attorney Kay Thurman volunteers on the project, helping to feed the beetles in the lab. She says it's gratifying to be able to work hands-on with an endangered species. "It isn't like I can go out and feed a cheetah, or save a cheetah," Thurman explains. "But this is really an opportunity for a volunteer to get in here and work directly with individual animals that we're trying to propagate and preserve here at the zoo."

Some of those beetles have been released in Ohio, to try to re-establish a population there. Others have been reintroduced on the island of Nantucket. And now, the U.S. Fish and Wildlife Service is considering proposals to try to re-establish more populations in other areas - including in Missouri.

Those reintroduction plans haven't been finalized yet. Bob Merz says in the meantime, he and his team will just keep doing their part to bring this endangered beetle back.

Beetle audio provided by Carrie Hall, Ph.D. candidate, Idaho State University.
Music credits: John Carpenter (Halloween movie theme); The Beatles (Get Back).