Carrion Beetles, Family Silphidae

Habits and Traits of Carrion Beetles

Burying beetle.
Burying beetle. Getty Images/Corbis Documentary/FLPA/Bob Gibbons

Look no further than your nearest road kill if you want to collect specimens in the family Silphidae. Carrion beetles inhabit the remains of dead vertebrates, munching on maggots and consuming the corpse. As gross as that sounds, it's an important job. Carrion beetles also go by the common names burying beetles and sexton beetles.

What Do Carrion Beetles Look Like?

Unless you’re in the habit of examining carcasses, you may never come across a carrion beetle.

Some species will fly to porch lights on summer evenings, so you may get lucky and find one on your front door. While we might find the carrion beetle’s diet rather distasteful, these scavengers provide a vital ecological service - disposing of carcasses.

Most of the carrion beetles we encounter fall into one of two genera: Silpha or Nicrophorus. Silpha beetles are medium to large, oval in shape, and usually flattened. They’re typically black, sometimes with a yellow pronotum. Nicrophorus beetles (sometimes spelled Necrophorus) are commonly called burying beetles, thanks to their remarkable ability to move and bury carcasses. Their bodies are elongate, with shortened elytra. Many burying beetles are red and black in color.

Though carrion beetles as a family range in size from just a few millimeters to as long as 35 mm, most species we commonly encounter top 10 mm in length. Silphids have clubbed antennae, and tarsi (feet) with 5 joints.

Carrion beetle larvae have elongated bodies that taper at the hind end.

How Are Carrion Beetles Classified?

Kingdom - Animalia
Phylum - Arthropoda
Class - Insecta
Order - Coleooptera
Family - Silphidae

What Do Carrion Beetles Eat?

As adults, most carrion beetles feed on maggots, as well as on the decomposing carcass they inhabit.

The adults’ voracious appetite for maggots certainly helps eliminate competition for their offspring. The carrion beetle larvae feed on the carcass, which would quickly be devoured by maggots without the intervention of the adult Silphids. A few carrion beetle species feed on plants, or even more rarely, prey on snails or caterpillars.

The Carrion Beetle Life Cycle

Like all beetles, Silphids undergo complete metamorphosis, with four stages of the life cycle: egg, larva, pupa, and adult. The adult carrion beetles lay eggs on or near a decomposing carcass. The young larvae emerge in about a week, and will feed on the carcass for up to a month before pupating.

Interesting Behaviors of Carrion Beetles

Burying beetles (genus Nicrophorus) practice remarkable feats of insect strength in an effort to beat the competition to the carcass. When a pair of burying beetles comes across a carcass, they will immediately go to work burying the body. A couple Nicrophorus beetles can completely inter a carcass as large as a rat in a matter of hours. To do so, the beetles plow the earth beneath the carcass, using their heads like bulldozer blades to push loose soil out from under the body. As more and more soil is excavated from beneath it, the carcass begins to settle into the ground.

Eventually, the burying beetles push the loose soil back over the body, effectively hiding it from competitors like blow flies. If the soil beneath the carcass proves to difficult to dig, the beetles may work together to lift and carry the body to another location nearby.

The bright bands of red or orange on the wings of many carrion beetles warn potential predators that they won’t make a very delicious meal, so don’t bother tasting them. There’s something to be said for the old adage “you are what you eat.” Carrion beetles, after all, feed on rotting flesh, and all the bacteria that goes along with it. Silphids apparently taste and smell like death.

Where Do Carrion Beetles Live?

The family Silphidae is a fairly small beetle group, with just 175 species known worldwide. Of these, about 30 species inhabit North America.

Most carrion beetles inhabit temperate regions.

 

Sources:

  • Borror and DeLong’s Introduction to the Study of Insects, 7th Edition, by Charles A. Triplehorn and Norman F. Johnson
  • Insects: Their Natural History and Diversity, by Stephen A. Marshall
  • Kaufman Field Guide to Insects of North America, by Eric R. Eaton and Kenn Kaufman
  • A Matter of Taste – The Natural History of Carrion Beetles, by Brett C. Ratcliffe, Curator of Insects, University of Nebraska State Museum
  • Family Silphidae, Bugguide.net, accessed November 29, 2011