While sitting in traffic on the Washington Beltway amidst the noise and pollution of rush hour traffic, I sometimes wonder about sights, sounds, and smells back in the day when horses and buggies transported folks through bucolic landscapes near the nation’s capitol. On a recent adventure to the great Kissimmee prairie in central Florida, I had the good fortune to witness a truly remarkable event that opened a window to times past when horses, mules, and oxen were the primary sources of transportation. While walking along a well-used bridle path and gingerly dodging piles of horse manure, I was delighted to see a beautiful beetle emerge from the soil, grapple with a clod of dung, and disappear with its prize beneath the earth.
This creature, the rainbow dung beetle, is a relative of other scarabs such as the Hercules beetle we met in previous episodes. However, this species specializes in using dung as the source of food for its young. Shortly after a horse or other large animal relieves itself, male and female dung beetles arrive at the scene and cooperate in excavating burrows in the earth near the deposit. Portions of the dung are pushed and pulled into subterranean chambers were the female deposits eggs. After a few days, eggs hatch and the small larvae consume the nutrient rich dung. When their development is complete, the larvae form pupal chambers and later emerge from their galleries to seek fresh patties of dung for babes of their own.
Dung beetles are generally considered highly beneficial by virtue of their ability to clean up after messy mammals. This highly desirable ecosystem service was clearly demonstrated in Australia. During colonial times, cattle were imported down under and after decades, thousands of tons of dung accumulated, despoiling vast acreages of pasture and providing breeding sites for flies and parasitic worms. In a series of carefully designed programs, dung beetles were collected from several countries in Europe and Africa and raised in Australian quarantine facilities to ensure that no harmful hitch-hikers accompanied them. After passing muster, the dung beetles were raised and released into the landscape to do what they do best - recycle dung. More than a million beetles representing some 20 species have been released for clean-up duty and the program is considered a resounding success.
Some good news, you do not need to visit Florida or Australia to discover dung beetles. They are relatively common in Maryland and were well known even in colonial times. One fascinating story of dung beetles in Maryland and their antics comes from the Callister papers written during the 1600’s. A translation of this account follows:
“A sort of Beetle; Their place of Rendezvous is always where fresh dung drops, and hundreds or two of them [appear]. One can hardly ease himself & turn about but he may see a hundred or more of ‘em roll themselves in the midst of it, & before tho there was not one to be seen before, & by the time he has button’d his breeches, turn again & is all gone; they join by pairs one lays an egg in the Dung & rolls it up into a ball the size of a marble & then another joins & sets to rolling it away like two sailors rolling a [hogshead] of Tobacco one always before pulling along the other behind shoving with his hind feet, & thus they roll & scatter the dung about till they find a proper place where they dig a hole 2 or 3 foot in the Ground, whichmay serve to manure the Ground, from whence the young one is produced in its proper time. Thus our Air is preserved sweet in the summer, from the Infection of Dungs.”
Ridding the world of dung is tough, dirty work, but the male Rainbow dung beetle is up to the task.
We thank Dr. Ellen Lawler for sharing the remarkable story of colonial dung beetles. The wonderful reference “Introduced Dung Beetles in Australia 1967-2007: current status and future directions” by Penny Edwards was also use in preparation of this week’s episode.