Deerly departed: food for flesh-recycling carrion beetles - Margined carrion beetle, Oiceoptoma noveboracense, and American carrion beetle, Necrophila americana

 

A margined carrion beetle takes a break from eating flesh and maggots to glam for the camera.

 

Through no fault of their own, white-tailed deer are a major pest of ornamental plants in our suburban and rural landscapes. It is estimated that in the US, more than 20 million deer share the land with us. When I see a dozen or so bedding down in my backyard, I think most of these rascals live in Columbia, Maryland. Long gone are the wild predators, mountain lions and wolves, that once kept burgeoning deer populations in check. Encroachment of human development on natural habitats put deer in contact with humans and their gardens. The grazing pressure of deer in my neighborhood has defeated all attempts at growing unprotected vegetables. During the winter, my pansies were pillaged and my once glorious azaleas were reduced to skeletal pickets of denuded branches presenting a few sad blossoms this spring. Small saplings bear the scars and deformities dealt by young bucks removing velvet from their antlers. The growing tips of my hopeful sunflowers and blueberries are but a memory. With all the undesirable changes deer bring to the suburban landscape, what is the upside of this pariah?

A nocturnal jaunt near a carcass reveals a pretty American carrion beetle caught in the beam of a flashlight.

One answer to this question appears in the final resting place of recently expired deer, the deerly departed so to speak. Several years ago while walking a field not far from a roadway traversing Etchison, Maryland, I noticed the earthly remains of a white-tailed deer resting in the tall grass, no doubt the unfortunate participant in an encounter with a vehicle on the nearby road. Upon closer inspection, I discovered a well-developed ecosystem of necrophagous insects making the most of the decaying bounty provided by the deer in its final act. Among the most prominent and abundant of these flesh eaters was Oiceoptoma noveboracense, commonly known as the margined carrion beetle. Along with flies and other species of beetles, carrion beetles provide an important ecosystem service by recycling the protein found in the flesh of dead animals. Carrion beetles are not usually the first to arrive at the carcass of a dead thing. This honor belongs to blow flies which often discover a body within minutes of its demise. Once colonized by blow flies, a dead animal will soon be writhing with maggots of flesh-eating flies. Maggots are an important source of food for adult carrion beetles. As they graze on the fleshy bounty, adult beetles occasionally deposit eggs in the soil near the carcass. Eggs soon hatch into larvae, youthful champions at consuming shreds of protein-rich flesh and internal organs of the deceased. By the time I happened across the deer, hundreds of beetle larvae were enjoying sustenance and shelter from the helpful deer.

In a previous episode we met bess beetles, one of the champion insect recyclers of wood. But in the wild more than wood is available for repurposing. Dead animals play an important role in food webs as rich sources of nutrients for the necrophagous species, eaters of the dead. Watch how a bountiful supply of deceased white-tailed deer reenters food webs with the assistance of flesh-eating carrion beetles.

A more recent discovery of a disarticulated deer along a bike trail revealed the carrion beetle’s dogged ability to remove even the last shreds of meat from a bone. After feeding as larvae and molting several times, larvae move to the soil to pupate. A bit later in summer, fresh adults will emerge from the soil and await the arrival of more dead animals ready for recycling. Due to their affinity for certain types of habitats, their patterns of seasonal appearance, and their geographic distribution, Oiceoptoma beetles can be useful in helping crime scene investigators solve homicides. Uplifting encounters with deceased white-tailed deer provided some succor to the ill will engendered by these habitat destroying herbivores. To bring more crime solving, flesh recycling beetles into the world is surely a noble final deed for the oft maligned white-tailed deer. 

References

Many thanks go to Kelly for allowing me to wander his fields and to Dr. Shrewsbury, who spotted the deer skull along the Western Maryland Rail Trail, for inspiring this episode. The delightful reference “The Carrion Beetles (Coleoptera: Silphidae) of Nebraska” by Brett Radcliffe was used as a resource.