The beetles beneath the groundWritten by George Ellison
“Ere the bat hath flown
His cloister’d flight … to black Hecate’s summons
The shard-borne beetle with his
Hath rung night’s yawning peal,
there shall be done
A deed of dreadful note.”
— Shakespeare, Macbeth
There are a number of beetle species known as carrion beetles because they feed upon the carcasses of dead animals. The most interesting ones within this general type are called burying or sexton beetles because they bury their food source before devouring it. One of the ancient duties of a church sexton was the digging of graves for deceased members, hence the same sexton beetle.
Burying beetles have a keen sense of smell that enables them to locate dead animals from considerable distances. A male that discovers carrion climbs on a stone or plant and signals his mate by emitting a special odor and a harsh rasping call.
Along a pathway near my home where I grew up in Virginia, I once saw a dead bird that appeared to be slowly sinking into the earth. This seemed unlikely so I sat down so as to observe what was going on. After the bird had sunk an inch or so below ground level, two glistening black beetles about 1-1/2 inches in length with red body patches emerged from below and commenced piling the excavated soil over the bird. Before long the burial was completed and the beetles themselves disappeared underground.
That sent me to an encyclopedia. Therein I read that once the carrion is buried the female beetle lays her eggs on or near the carcass. When the hatched larvae are large enough to do so they feed on the carcass.
If the soil below a carcass that’s been located is soft, burying beetles go right ahead and conduct the burial on that site. If the ground is unduly hard or rocky, they pitch in as a team and move it to a more suitable place. The male and female laboriously roll their find by butting it over and over. Another carcass-moving technique they utilize is to turn over on their backs and apply leverage with all six of their powerful legs at once. A pair of burying beetles have been known to move a large rat several feet in order to find a suitable burial ground.
In “Macbeth,” Shakespeare associated “shard-borne beetles” (those with hard wing cases) with “night’s yawning peal” and deeds of “dreadful note” such as murder. But as gruesome as their role in the natural order of things may at first seem, the contribution burying beetles make to the recycling of energy systems is — in the long run — life giving.
Unfortunately, the populations of American burying beetles have declined to such an extent that seeing one these days is much less likely than when I was a boy.