Beetles Used to Strip Animal Carcasses Down to Bones

FAIRBANKS, Alaska – Beneath the lids of large coolers, thousands of tiny bugs devour the desiccated flesh of mammal carcasses destined for the vast specimens collection at the University of Alaska's Museum of the North.

As they gnaw away, the stench is overwhelming, a rancid sweetness that stings the eyes and lungs, clinging to hair and clothes like a vile perfume.

This is the smell of global warming research at work. The dermestid beetles have been used for decades by museums to clean bones because of their unmatched ability to strip them without damaging even the smallest, most delicate specimens.

The skill also makes them valuable to scientists studying global warming, because they are capable of unveiling the most minute changes in a species.

Though use of the beetles is common across the country, their talent is increasingly crucial in preparing specimens from the Arctic, where effects of warming appear first and with greater intensity. The Fairbanks museum is the largest U.S. repository for high-latitude species.

"Dermestids may be low-tech, but there's no other method that does as good a job of cleaning skulls and skeletons for long-term archival preservation," said Link Olson, curator of the museum's mammals collection and a biology professor at the university.

Global warming researchers often have to look for tiny clues in bones to help them understand even the most minute effects of climate change on animals. Cleaner bones can give them a more accurate picture of changes.

These drab little bugs are common household pests that eat through furs, clothing and cereal, shedding their telltale exoskeletons in drawers and cupboards. At the Fairbanks museum, the "bug room" is secluded from the museum's larger collection out of necessity.

A dermestid infestation is a curator's worst nightmare. There's not much the bugs won't eat.

That much was evident on a recent evening when Olson and mammals collection manager Brandy Jacobsen brought in frozen pieces of a musk ox.

Seemingly oblivious to the smell, Jacobsen set an ox leg and other chunks of meat under a range hood, where they would air dry for at least two days. Otherwise the meat would be too wet for the carrion-eating bugs, which were busy crawling all over the skull of a Sitka blacktail deer and the bones of other mammals, including a polar bear.

"They only eat dead flesh," Olson said. "They like jerky, basically."

Scientists also say the dermestid method is preferable to other methods of cleaning bones, such as maceration, in which bones are soaked in bacteria-laden water to break down soft tissue. That can loosen teeth or weaken sutures in skulls or long bones, Larry Heaney, curator of the division of mammals at the Field Museum of Natural History in Chicago.

Their cleaning prowess is invaluable when measuring changes over extended periods of time, he said. Researchers are often looking for tiny changes in density, proportion, shape and size of bones, which can reflect changes in resources available to the animal.

Israeli scientist Yoram Yom-Tov recently used 400 marten specimens obtained by the museum during the last 50 years to determine that the small carnivore had grown over the years by a few percentage points.

The most plausible explanation for the growth is that winters are shorter and warmer, said Yom-Tov, a professor of zoology at Tel-Aviv University. With a longer growing season in the Arctic, plants are more available to such prey as voles, so they become bigger and more plentiful, supplying a greater source of food for martens, he said.

"What researchers are often looking for at this point are very subtle changes taking place," Heaney said. "With specimens cleaned by beetles, you can look very precisely at tiny changes in the anatomy of the animals."

As for the smell?

"It gets more bearable as you get used to it," Jacobsen said.