While sitting in traffic on the Washington Beltway amidst the noise and pollution of rush hour traffic, I sometimes wonder about sights 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 bridal path 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, and American rhinoceros beetle we met in previous episodes. However, this species specializes on 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 out 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, although some dung beetles act as hosts for parasites of swine. Some good news, you do not need to visit Florida to discover dung beetles. They are relatively common in Maryland and were well known even in colonial times. One fascinating story of dung beetles and their antics comes from the Callister papers written during the 1700’s. A translation of this account follows. “Some account of the most remarkable Curiosities of Maryland, or the Rarities of the New World” “A sort of Beetle; Their place of Rendezvous is always where fresh dung drops, and hundreds or two of them. 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 [Lhd.] 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, which may 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.”
We thank Dr. Ellen Lawler for sharing the remarkable story of colonial dung beetles. The interesting reference “Beetle intermediate hosts for swine spirurids in southern Georgia” by G.T. Fincher, T.B. Stewart, and R. Davis was also use in preparation of this week’s episode. To learn more about dung beetles, please visit the following web site.