Dung beetle
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Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Superfamily: Scarabaeoidea
Families: Scarabaeidae, Geotrupidae

[Photo] Scarabaeus laticollis near a nuraghe near Monte Tiscali, Sardinia, Italy. Date 2006-04-12. Author Rafael Brix. URL: http://en.wikipedia.org/wiki/Image:Scarabaeus_laticollis_2.jpg

Copyright (C) 2006 Rafael Brix Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

Dung beetles (also known as tumble bugs) are beetles which feed partly or exclusively on feces. All of these species belong to the superfamily Scarabaeoidea; most of them to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae. As most species of Scarabaeinae feed exclusively on feces, 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
The size of a dung beetle varies from species to species. The "dwellers" are usually small and elongate. Dung beetles are basically black, brown or purplish yellow in color; some are of metallic luster, especially the tropical species. Most dung beetles have a flattened, but stout body. The male of some species has horns at the head or thorax. Some dung beetles, other than the "dwellers", 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 labor 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 behavior
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 excreted 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 or drink anything else because the dung provides all the necessary nutrients. 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 such as dung-feeding maggots that sometimes get trapped between their mandibles).

Most dung beetles search for dung with the aid of their strong sense of smell. Some of the smaller species, however, simply attach themselves to the dung-providers to wait for their reward. After capturing the dung, a dung beetle will roll it, following a straight line despite all obstacles. Sometimes dung beetles will try to steal the dung ball of another beetle, so the dung beetles have to move rapidly away from a dung pile once they have rolled their ball to prevent it from being stolen. In 2003, researchers found that a species of dung beetle navigates by using polarization patterns in moonlight. The species in question is the African Scarabaeus zambesianus. The discovery is the first proof that any animal can use polarized moonlight for orientation.

The "rollers" roll and bury a dung ball either for food storage or for making a brooding ball. In the latter case, two beetles, one male and one female, will be seen around the dung ball during the rolling process. Usually it is the male that rolls the ball, with the female hitch-hiking or simply following behind. In some cases the male and the female roll together. When a spot with soft soil is found, they 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 finished, the female lays eggs inside it. Some species do not leave after this stage, but remain to safeguard their offspring.

The dung beetle goes through a complete metamorphosis. The larvae live in brood balls made with dung prepared by their parents. During the larval stage the beetle feeds on the dung surrounding it.

The behaviour of the beetles was much misunderstood, until the pioneering studies of Jean Henri Fabre. For example, Fabre corrected the myth that a dung beetle would seek aid from other dung beetles when confronted by obstacles. By painstaking observations and experiments, he found that the seeming helpers were in fact robbers awaiting an opportunity to steal the roller's treasure:

"I ask myself in vain what Proudhon introduced into Scarabaean morality the daring paradox that "property means plunder", or what diplomatist taught the Dung-beetle the savage maxim that "might is right".

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 livestock, such as cattle, by removing the dung which, if left, could provide habitat for pests such as flies. Therefore, many countries have introduced the creature for the benefit of animal husbandry. In developing countries, the beetle is especially important as an adjunct for improving standards of hygiene. The American Institute of Biological Sciences reports that dung beetles save the United States cattle industry an estimated US$380 million annually through burying above-ground livestock feces.

Like many other insects, the (dried) dung beetle, called qianglang (??????) in Chinese, is used in Chinese herbal medicine. It is recorded in the "Insect section" (蟲部) of the Compendium of Materia Medica, where it is recommended for the cure of 10 different diseases.

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