Common Name: Tumblebug, Scarab beetle, Dung beetle – The beetle forms a ball of dung that is large relative to its size and rolls it some distance from the point of origin, frequently falling over in the process due to uneven terrain, obstructions and the unwieldy nature of the burden. The tumbling in transport is the source of the common name – a bug that tumbles..
Scientific Name: Canthon Spp – Probably from the Greek kanthos which means corner of the eye; the juncture of the elytra (wing covers) has the appearance of the canthus, the crease at the edge or corner of the eye. Family: Scarabaeidae – the family name from which the common name scarab is derived is from the Greek karabos, a horned beetle.
Potpourri: Of the approximately 30,000 species of scarab family beetles worldwide (1,200 in North America), about 5,000 are in the subfamily Scarabaeinae that feed exclusively on dung; they are therefore called true dung beetles. The subfamily is sometimes trisected according to the manner in which the dung is collected: dwellers live in the manure, tunnellers dig tunnels under or near the manure pile and roll balls into it and rollers (tumblebugs) have an independent underground burrow or nest and must therefore form a coherent spherical ball and roll it some distance away. Though the consumption of feces is considered anathema to the human notion of edibility, the ubiquity and nutrient value of egested waste products make it an attractive food source for many insects.
The tumblebugs are especially adept at their chosen métier, the transport and deposition of manure; an average daily sequestration rate of 60 cubic inches of excrement has been recorded – about the volume of the average cow pie. Were it not for the food preferences of some insects, much of the worlds pastureland would be knee-deep in excrement. For example, when cattle were first imported to Australia in the 19th Century, the native dung beetles could not keep up, as they were adapted to the meager droppings of the native fauna. (As an interesting side note, one Australian dung beetle, Macrocopris symbioticus, lives in the anus of the wallaby, hanging on with its clawed forelegs). Due to the inadequacy of the native scavenging dung beetles, it took up to five years for the dung to decompose (compared to a few weeks in North America). When the loss of pastureland resulted in the loss of millions of dollars of revenue, it became apparent that action was necessary; a scarabaeid species was introduced from Africa. Dung beetles are accordingly considered beneficent in that they dispose of fecal material that would otherwise accumulate and become a haven for other less desirable insects such as flies, all the while contributing to the distribution of the manure to restoration of nutrients to the soil. The tumblebug’s manure ministrations purportedly save the U. S. cattle industry 380 million dollars every year by burying about 80 percent of all depositions.
The physiology of the tumblebug is well suited to the task of forming and transporting a ball of dung; it is robust and solidly built with a spade-shaped head and flattened paddle-like antennae that are used to shape the ball, giving it a hard outer crust to protect it from disassociation and desiccation during transport. Once formed the ball is pushed with the hind legs with the forelegs braced against the ground, so that the beetle almost stands on its head; it is no wonder that the process results in frequent tumbles. The ball is moved some distance away and a hole is dug into which the ball is deposited and buried for protection from competing coprophagous insects. The dung beetle can eat more than its own weight in every 24 hour period, so this process needs to be repeated during the summer months as the adult beetles progress and mature.
The remarkable behavior of the dung beetle was observed and documented by Jean Henri Casimir Fabre, who is widely recognized as the father of experimental entomology. For about forty years, he studied the behavior of insects on his property at Serignan in southern France, publishing his findings in a series of ten volumes entitled Souvenirs Entomologiques (insect memories). His work with Sisyphus beetles that feed on sheep dung was especially noteworthy. In Greek mythology, the deceitful Sisyphus was doomed to push a heavy boulder up a hill only to have it roll back down every time the summit was reached – a much better metaphor for the tumblebug. Fabre recorded the behavior of male and female beetles in the transport of the a ball of sheep dung for deposition of the eggs, which occurs at the end of the summer. They worked together to make the ball and roll it some distance; the female then dug the hole into which the ball was deposited. The two subsequently climbed into the pit with the ball and continued digging until they were well underground with the ball. After several days, the beetles reemerged, first the male and then the female, proceeding back to the original manure pile for another dung ball. Fabre carefully excavated the site to find that the ball had been kneaded into a pear shape and that a single egg had been laid in the narrow neck, the monogamous couple proceeding in the formation of a second ball for the next incubation. The life cycle of the dung beetle was thus well established: the egg hatches into a C-shaped grub or larva and subsists wholly on the dung inside the ball, consuming the interior until a hollow shell remains. At this point, it pupates to emerge in the spring as an adult, normally after a rain, and digs out of its burrow to the surface – and begin the search for dung.
In an experiment with the scarab (Scarabaeus sacer), Fabre noted a second behavioral anomaly that would suggest a measure of intelligence. During the normal course of the dung collection and sequestration process, a dung beetle will frequently take on a partner, presumably to help with the arduous chores of transport and burial. However, the second beetle is typically fainéant, doing nothing but observing the assiduous beetle do almost all of the work. Fabre observed that the lazy beetle would “stand guard” over the dung ball as the process of digging the hole for the deposition of the dung ball was initiated by the worker beetle. Once the hole was deep enough to provide for concealment, the indolent partner would attempt to make off with the ball, only to be confronted by the astonished worker beetle on discovery of the subterfuge. The end result was either one of mutual conciliation or a fight in which the winner claimed the spoils in their entirety. Fabre conducted a test of the fealty of the beetle partners by affixing the dung ball to the ground with a pin. After trying to mutually push the ball against the immovable pin, the partner beetles conspired to dig under the ball and thereby effect its release by lifting it off the pin and proceeding with the originally intended transport and burial.
The scarab is clever in an entomological sense and sacerdotal in an historical sense; the ancient Egyptians apotheosized the scarab as a god. The etiology of the dung beetle deity belief is not known, though it is surmised that the ancient Egyptians observed the scarab along the banks of the Nile and marveled at its unusual behavior. The dung ball came to symbolize the sun (in some texts the earth) that the scarab pushed across the ground until burying it. They believed that the dung beetles were all male and that they implanted their semen directly inside the ball to transform into the regenerative seed. Its lifecycle thus became a microcosm of death and rebirth; on the cosmological scale, this manifested itself in the daily death and rebirth of the sun. The diurnal repetition of the movement of a ball, its disappearance and its ultimate reformation paralleled the movement of the sun, the scarab thus taking on a divine aura.
The Egyptian sun god had numerous guises: Aten the solar disk, Khepri the rising sun, Ra the sun climbing to the zenith, and Atum the setting sun, ultimately becoming a combination of Ra and Horus and reigning over all of Egypt as Ra-Harakhte. It was the rising sun god Khepri that the scarab came to symbolize; like the scarab the sun was reborn from its own being. Khepri was “he who becomes” and is frequently depicted as having a scarab face, perhaps the only deity in the historical record from the phylum Arthropoda. The scarab became an object of both practical and religious importance in Egypt. In the Old Kingdom (2686-2160 BCE) glazed steatite scarabs were used as seals with a cartouche, or legend, to indicate the title of the official whose approval was indicated. During the later years of the New Kingdom (1567-1085 BCE), the scarab symbol became an amulet and was frequently incorporated into the funerary process, probably symbolizing eventual metempsychosis as this was the nature of the association.