Flesh Eaters Burying Beetles Make Meals—And Temporary Homes—Out of Dead Animals

Young naturalists ▼ Flesh Eaters Burying beetles make meals—and temporary homes—out of dead animals.

By Christopher E. Smith I encountered my first burying es, had distinct habits, and lived in beetle, a small black and orange in- many kinds of habitat. The more sect, about 10 years ago, when I hap- I explored this group of beetles, pened across a dead squirrel at the the more I got hooked. Since my edge of my yard. Being the curious original burying beetle encounter, person that I am, I poked and prod- I earned college degrees in wild- ded the squirrel, eventually rolling life management and conserva- it over to see what it looked like tion biology, including a minor in underneath. Much to my surprise, entomology, the study of insects. several small beetles scurried away, I now work as a wildlife biologist including a few with bright orange studying amphibians, reptiles, markings on their backs and yellow and insects—the creepy-crawlies hairs on their necks. That evening I I find fascinating. went online to search for the iden- There are about 70 species, or tity of the beetles and found what kinds, of burying beetle worldwide. they were—gold-necked burying About 17 of them can be found beetles (Nicrophorus tomentosus). in the United States, and at least It turned out the gold-necked bury- 11 of those can be found in Min- ing beetle is attracted to and then nesota. Wherever an animal has feeds on dead things. died and begun to rot and stink, I soon learned I could find other these beetles can be found making species of burying beetles in the their home. Let’s take a look at why area. These relatives of my back- burying beetles are so well suited

ERICA HOAGLUND yard beetles came in different siz- for living amid death.

60 Minnesota Conservation Volunteer May–June 2019 61 Dozens of burying beetles crawl around in a baited pitfall trap. The smell can attract burying beetles from miles away. CHRISTOPHER SMITH CHRISTOPHER Nature’s Gravediggers

CHRISTOPHER SMITH CHRISTOPHER Once they are in control of a carcass, the Once the carcass is underground, things A baited pitfall trap (left) sits at the ready. After beetles fall into the bucket under the protective top, beetles typically begin removing the soil start to get really gross. The beetles work they are identified and then let go. The smell of dead rats (right) attracts beetles. underneath the corpse using their power- together to remove fur or feathers and ful legs and mouthparts. As they patiently chew up the carcass while rolling it into In Search of Fresh Flesh dig, the carcass slowly lowers below the soil a ball. They sometimes have to compete Burying beetles were crawling on the dead ing beetles are strong flyers, and some surface, and the soil collapses over the top with maggots, the larvae of flies, for the squirrel in part to feed on one of their fa- species are able to fly several miles in a of the carcass. This is why they are called flesh. The beetles have a secret weapon, vorite foods: rotting flesh, orcarrion . Eat- single night in search of food. They use burying beetles. though: hitchhiking mites! These small, ing dead things is a habit burying beetles their powerful sense of smell to detect The beetles bury their food to prevent orange mites hitch a ride on the much share with their relatives, carrion beetles. odors of rotting flesh in the air. Once larger scavengers, like vultures or rac- larger burying beetles, traveling between Burying beetles aren’t too picky about the burying beetles find the dead body, coons, from stealing it, and to protect carcasses. type of flesh, eagerly eating dead small or carcass, of a small animal, they may the young beetles that will eventually be When the beetle lands on a carcass and mammals, birds, amphibians, and reptiles. have to battle with other burying beetles raised on the carcass. If a scavenger finds buries it, the mites, called phoretic mites, They also eat other things that don’t sound for the prize. Male and female burying the carcass before it’s buried, or if the car- crawl off and begin feeding on the fly eggs too good to us, including poop, rotting beetles will often pair up to battle, a type cass is too large to bury, the beetles have and maggots, reducing competition for vegetation, and other insects. of cooperation that is rare in the world to be able to escape before they too be- the beetles. In exchange for the maggot In order to eat their dead treats, the of beetles. The largest male and female come part of the meal. Because of this control, the mites get a free taxi ride be- beetles must first find them—and they typically emerge as the winners to feed risk, they flee the carcass if they feel vi- tween meals—a win-win tradeoff that is have special tools for doing this. Bury- and reproduce on the carcass. brations nearby. called a symbiotic relationship.

62 Minnesota Conservation Volunteer May–June 2019 63 The life of a iesta ryig eetle Adults emerge from pupal shells several weeks later, ready to fly off Adults can fly several miles in one night searching for food. They detect to find a new carcass the scent of a dead animal carcass with chemosensors in their antennae.

2 colorful, hard, and shiny Larvae burrow into soil and pupate. fore wings used for protection Adults emerge from pupal skin in several weeks. 2 transparent back wings used for flying Eye Clubbed antenna Larvae hatch from the eggs in a few days and the adults feed Head the larvae for several days, like bird parents feed their chicks

6 legs

Abdomen icrophorus Beetle Anatomy

Arriving at a carcass, adults battle for ownership of the dead animal, which they will use as a food source and breeding site They chew up the body until it is soft enough to roll into a ball Female digs a small side chamber and lays about 30 eggs A male and a female work together to bury the carcass by digging below it to form a pit chamber

They snip off fur or feathers and use the materials to line the pit

64 BILL JOHNSON TOM RATZ TOM

Mites (top) catch a ride on a round-necked burying beetle. Burying beetles are dedicated parents. An MIKE DVORAK adult boreal burying beetle (bottom) cares for its young much like a bird cares for its babies. Burying beetles help transfer nutrients below ground, feeding microbes, fungi, and plants. Carcass Sweet carcass The Recyclers While the mites are busy eating maggots wormlike grubs to fully formed adult bee- Whether you find burying beetles ex- By consuming carrion, burying beetles and reproducing, the burying beetles tles, similar to the way some caterpillars tremely disgusting or absolutely fascinat- help transfer nutrients from previously lay eggs in the underground chamber transform into butterflies. ing, like I do, they play important roles in living animals into the soil. This transfer that now contains a blob of mushy, rot- As the new adult beetles begin to dig nature. Burying beetles are decomposers— of nutrients from the aboveground to the ting flesh. Once the beetle eggs hatch, the their way out from their underground a species that helps break down and re- belowground world helps sustain life on adults feed the larvae, called grubs, by re- chamber, the mites that have been living cycle materials into smaller parts that can earth. In addition to transferring nutrients, gurgitating what is basically rotting ooze, alongside them climb aboard to travel to be used by other plants and animals. The decomposers help clean up the above- much like birds feed their young. the next meal. The beetles may feed for animal carcasses that are broken down by ground environment, which helps prevent After feeding voraciously for several several weeks before finding a place to hi- burying beetles become part of the soil to the spread of disease, including diseases days, the grubs pupate, transforming from bernate for the winter. be used by plants and microbes. that can make people sick.

66 Minnesota Conservation Volunteer May–June 2019 67 The American burying beetle is a federally endan- gered species and the largest species of burying beetle in North America. Once widespread, this beetle is now found only in isolated locations across the central and eastern United States. ERICA HOAGLUND The author checks a pitfall trap and documents the kinds and number of burying beetle present. JACOB FARRIESTER JACOB Spot a Beetle The Missing Beetle As a scientist who studies these beetles, I When I find or trap a burying beetle, I Historically, Minnesota had 12 species died, it was the perfect-sized meal for the have two favorite ways to find them. One is look for clues to identify which one of Min- of burying beetles, more kinds than any beetle to raise its young on. When the pas- to look under dead things I find while I’m nesota’s beetle species I’ve found. Unlike other state in the nation. However, one, senger pigeon went extinct, the American out hiking around. I look for dead fish or many insects that require a great deal of ex- the American burying beetle (Nicropho- burying beetle may have been an unex- fish parts near popular fishing spots, and perience to learn to identify, burying beetle rus americanus), is presumed to be wiped pected additional casualty. near roads I keep an eye out for roadkill identification can be learned by anyone out, or extirpated, from Minnesota and Though Minnesota has lost this bury- squirrels, raccoons, rabbits, and other small with a little patience and a strong stomach. from much of its historical range. It was ing beetle, it may soon gain another one. to medium-sized animals. When I find a To identify Minnesota’s burying beetles, last seen in the state in the late 1960s near The Carolina burying beetle Nicrophorus( carcass, I grab a short stick and roll it over I’ve even developed an illustrated key to St. Cloud. Scientists have several different carolinus) has been found near the Min- to investigate. You too can do this to find help! Find it online at fieldecology.com/blog/ ideas about why it’s gone. One of the more nesota border in neighboring states to the burying beetles if you find a small dead burying-beetles. interesting ones is that it was a ripple effect west. It could turn up in western Minne- animal, but don’t touch the carcass or the One clue is the size and shape of the or- of the extinction of the passenger pigeon sota along the upper Minnesota River or beetles with your bare hands. ange markings on the beetle’s black wing in the early 1900s. the Red River of the North. Another, more effective way that I find shields. Another is the color of the tip of the Before its disappearance the passenger Maybe a young naturalist like you will burying beetles is to set baited traps be- antenna, or antennal club. If you get really pigeon was abundant, and when a pigeon be the first person to find it! nV tween June and August. I bury 5-gallon interested in identifying burying beetles, buckets in the ground and put dead rats in you can learn to trap, handle, and identify the bucket to attract the beetles. beetles yourself with the help of an adult. eachers resources. Find a Teachers Guide and other resources for Tthis and other Young Naturalists stories at mndnr.gov/young_naturalists. 68 Minnesota Conservation Volunteer May–June 2019 69