Dung beetle
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Image:Dungbeetle.jpg Dung beetles refer to those beetles which feed partly or exclusively on dung. Most of these species belong to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae. As most species of Scarabaeinae feed exclusively on dung, that subfamily is often dubbed true dung beetles. There are dung-feeding beetles which belong to other families, such as the Geotrupidae (the earth-boring dung beetle). The Scarabaeinae alone comprises more than 5,000 species.
Many dung beetles, known as rollers, are noted for rolling dung into spherical balls, which are used as a food source or brooding chambers. Other dung beetles, known as tunnellers, bury the dung wherever they find it. A third group, the dwellers, neither roll nor burrow: they simply live in manure.
Appearance
Image:Dung beetle Geotrupes sp.jpg The size of a dung beetle varies from species to species. The "dwellers" are usually small and elongate. Dung beetles are basically black or brown in colour; some are of metallic lustures, especially the tropical species. Most dung beetles have a flattened, but stout body. The male of some species has horns at its head or thorax. Besides the idle "dwellers", dung beetles have strong, often "toothed" legs specialised for rolling dung and burrowing. The tarsi at the forelegs of an old dung beetle are usually damaged or lost owing to the labour of burrowing - some species do not have tarsi at the forelegs at all. The desert species also have hair on the legs which facilitates their movement on sand. Dung beetles have soft mouthparts suited to their diet.
Ecology and behaviour
Dung beetles live in many different habitats, including desert, farmland, forest, and grasslands. They do not like extremely cold or dry weather. They occur on all continents except Antarctica.
Dung beetles eat dung released by herbivores and omnivores, and prefer that produced by the former. Many of them also feed on mushrooms and decaying leaves and fruits. They do not need to eat anything else because the dung provides all the nutrients. They do not even need to drink water. The larvae feeds on the undigested plant fiber in the dung, while the adults do not eat solid food at all. Instead they use their mouthparts to squeeze and suck the juice from the manure, a liquid full of micro-organisms and other nutrients (as well as the body fluids from some unlucky animals like dung feeding maggots who sometimes gets trapped between their mandibles).
Most dung beetles look for dung with the aid of their strong sense of odor. Some of the smaller species, however, simply claw onto the dung-providers to wait for their reward.
The dung beetle has complete metamorphosis. The larvae lives in a brood ball made with dung prepared by their parents. During the larval stage the beetle feeds on the dung surrounding it.
The "rollers" roll and burrow a dung ball either for food storage or for making a brooding ball. In the latter case, two beetles, one male and one female, can be seen around the dung ball during the rolling process. Usually it is the male which rolls the ball, with the female hitchhiking or simply following the ball. In some cases the male and the female roll together. The rolling route must be a straight line, despite all obstacles. During the rolling process, other dung beetles may attempt to rob the ball. The attacker is usually a male. An ensuing fight is not uncommon. After the combat, the separated couple joins and continues their labour. When a spot with soft soil is found, the couple will stop and bury the dung ball. They will then mate underground. After the mating, both or one of them will prepare the brooding ball. When the ball is made, the female will then lay its eggs inside the ball. Some species will not leave after this stage, but stay and safeguard their offspring.
The behavior of the beetles was much misunderstood, until the pioneering studies of Jean Henri Fabre. For example, Fabre dismissed the myth that a dung beetle would seek aid from other dung beetles when it, rolling the dung ball, was baffled by obstacles. By painstaking observations and experiments, he found that the seemingly co-workers were but robbers who came uninivited to wait for their chances, lamenting:
Vainement, je me demande quel est le Proudhon qui a fait passer dans les moeurs du Scarabée l'audacieux paradoxe : «La propriété, c'est le vol» ; quel est le diplomate qui a mis en honneur chez les bousiers la sauvage proposition : «La force prime le droit.» ... ("Le Scarabée sacré", dans Souvenirs entomologiques, Série I, Chapitre 1)
Benefits and uses
Dung beetles play a remarkable role in agriculture. By burying and consuming dung, they improve nutrient cycling and soil structure. They also protect such livestocks as cattle while removing dung, which is the hotbed for such pests as flies. Therefore, many countries have introduced the creature for the benefit of animal husbandry. For developing countries, the beetle is especially important for hygienic reasons.
Like many other insects, the (dried) dung beetle is used in Chinese medicine, believed to have appeasing and relieving effects.
Scarab in Ancient Egypt
Several species of the dung beetles, most notably the Scarabaeus sacer (often referred to as scarab), enjoyed a sacred status among the ancient Egyptians. Some scholars suggested that the people's practice of making mummy was inspired by the brooding process of the beetle. Template:HieroThe hieroglyphic image of the beetle is believed to represent a trilateral phonetic that Egyptologists transliterate as xpr or ḫpr and translate as "to come into being", "to become" or "to transform". The derivative term xprw or ḫpr(w) is variously translated as "form", "transformation", "happening", "mode of being" or "what has come into being" depending on the context. It may have existential, fictional, or ontologic significance.
The scarab was linked to Khepri ("he who has come into being"), the god of setting sun. The ancients believed that the dung beetle had only male, and reproduced by burying its semen into a dung ball. The supposed self-creation of the beetle resembles that of Khepri, who also creates himself out of nothing.
Moreover, the dung ball rolled by a dung beetle resembles the sun. Many authors suggest that the ancient Egyptians believed that Khepri renewed the sun every day before rolling it above the horizon and carried it through the other world after sunset to renew it the next day. Some New Kingdom royal tombs exhibit a threefold image of the sun god, using the beetle as symbol of the morning sun. The astronomical ceiling in the tomb of Ramses VI portrays the nightly "death" and "rebirth" of the sun as being swallowed by Nuit, goddess of night, and re-emerging from her womb as Khepri.
The image of the scarab, encoding ideas of transformation, renewal, and resurrection, is ubiquitous in ancient Egyptian religious and funerary art.
Excavations of ancient Egyptian sites have yielded images of the scarab in bone, ivory, stone, Egyptian faience, and precious metals, dating from the Sixth Dynasty through Roman rule. They are generally small items, bored to allow stringing on a necklace, and the base bears a brief inscription or cartouche. Some have been used as seals. Pharaohs sometimes commissioned the manufacture of larger images with lengthy inscriptions, such as the commemorative scarab of Queen Tiye. Massive sculptures of scarabs can be seen at Luxor Temple, at the Serapeum in Alexandria (see Serapis) and elsewhere in Egypt.
The scarab was of prime significance in the funerary cult of ancient Egypt. Scarabs, generally though not always cut from green stone, were placed on the chest of the deceased. Perhaps the most famous example of such "heart scarabs" is the yellow-green pectoral scarab found among the grave goods of Tutankhamen, carved from a large piece of Libyan desert glass. The purpose of the "heart scarab" was to ensure that the heart would not bear witness against the deceased at judgement in the Afterlife. Other possibilities are suggested by the "transformation spells" of the Coffin Texts, which affirm that the soul of the deceased may transform (xpr) into the semblance of a human being, a god, or a bird and reappear in the world of the living.
One scholar comments on other traits of the scarab connected with the theme of death and rebirth: "It may not have gone unnoticed that the pupa, whose wings and legs are encased at this stage of development, is very mummy-like. It has even been pointed out that the egg-bearing ball of dung is created in an underground chamber which is reached by a vertical shaft and horizontal passage curiously reminiscent of Old Kingdom mastaba tombs." (Andrews, Amulets of Ancient Egypt, p. 51.)
In contrast to funerary contexts, some of ancient Egypt's neighbors adopted the scarab motif for seals. The most well-known of these being Judean LMLK seals (8 of 21 designs contained scarab beetles), which were used exclusively to stamp impressions on storage jars during the reign of Hezekiah.
The scarab remains an item of popular interest thanks to modern fascination with the art and beliefs of ancient Egypt. Scarab beads in semiprecious stones or glazed ceramics can be purchased at most bead shops, while at Luxor Temple a massive ancient scarab has been roped off to discourage visitors from rubbing the base of the statue "for luck".
In literature
In Aesop's fable "The dung beetle and the eagle", the eagle kills a hare despite the beetle's appeals. The beetle takes revenge by destroying the eggs of the eagle twice. The eagle, in despair, flies up to Olympus and placed its eggs in Zeus's lap, praying the God to protect the eggs. When the beetle finds out what the eagle has done, it stuffs itself with dung, goes straight up to Zeus and flies right into his face. At the sight of the unpleasing creature, Zeus is startled and jumps to his feet. The eggs are broken once again. Zeus then learns of the wrong that has been done to the beetle. He scolds the eagle, and urges the beetle to leave the eagle alone. When his efforts to persuade the beetle fails, he changes the breeding season of the eagles - it is to take place at a time when the beetles are not found above ground.
Aristophanes alluded to Aesop's fable several times in his plays. In Peace, the hero rides up a dung beetle, which has been fed up with dung until it grows into a monstrous size, to Olympus to free the goddess Peace from her prison.
References
- Carol Andrews. Amulets of Ancient Egypt. University of Texas Press, 1994. ISBN 0-292-70464-X.
- Hannes Buchberger. Transformation und Transformat. Sargtextstudien I, Wiesbaden, Harrassowitz Verlag, 1993. ISBN 3-447-03078-X.
- Jean-Henri Fabre. Souvenirs entomologiques: étude sur l'instinct et les moeurs des insectes, Tome 1 et 2. Robert Laffont: Bouquins, 2000. ISBN 2221054628, ISBN 2221054636.
- Raymond O. Faulkner. A Concise Dictionary of Middle Egyptian. Oxford: Griffith Institute, 2002. ISBN 0-900416-32-7.
- Gonzalo Halffter and Eric G. Matthews. The natural history of dung beetles: Of the subfamily Scarabaeinae. Folia Entomologica Mexicana, 1966.
- Ilkka Hanski, Yves Cambefort. Dung Beetle Ecology. Princeton University Press, 1991. ISBN 0691087393.
- John H. Taylor. Mummy: The inside story. The British Museum Press, 2004. ISBN 0-7141-1962-8.
- Richard H. Wilkinson. Symbol & Magic in Egyptian Art. London: Thames and Hudson Ltd., 1994. ISBN 0-500-23663-1.