Family Scarabaeidae - Phanaeus difformis

Phanaeus difformis
Range: southwestern United States
Size: 20 mm

Phanaeus is a genus of scarab which belongs to the subfamily "scarabaeinae", commonly known as the dung beetles. Its thoracic shield is a striking metallic green colour. The male of this species has a single, upward projecting horn on its head. The female has a wide, shovel shaped flange (the clypeus) on the front of the head which is used for scooping dung or moving soil when excavating a brood chamber for its larvae. Phanaeus is a scarab of the type that was familiar to the ancient Egyptians, and its image was a central motif in their art. A close relative of Phanaeus, the sacred scarab, (Scarabaeus sacer) is likely the species which served as their model.

An ancient Egyptian amulet
which depicts a scarab beetle (Scarabaeus) which is quite
similar in form to Phanaeus.

Adult female Phanaeus beetles form spheres of herbivore dung by shaping it with their forelegs. These spheres are created from pieces of dung that have been pulled into an underground chamber which the beetle has excavated. A single egg is deposited within each dung sphere, and the resultant larva is sustained throughout its life cycle by the nutrients contained within the dung. As the larva grows and consumes the dung inside, the sphere eventually becomes hollow. After metamorphosing to the adult stage within the sphere, the adult hatches out to begin the life cycle again.

Phanaeus sp. - female - Image © C. Campbell

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Female Phanaeus sp.
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Africa has an especially large number of dung beetle species. In some parts of the world, such as Australia and the United States, African dung beetles have been intentionally introduced to help reduce the amount of cattle dung on ranches. This greatly helps to reduce the numbers of bothersome flies which use dung as food during their larval stage. Because the beetles deprive the flies of their food source by burying it, this is a simple and effective means of biological fly control. The United States and Australia have their own unique species of dung beetles however, and the impact that introduction of non-native dung beetle species has had on them is still largely unknown.

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Female Phanaeus sp.
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Phanaeus sp. - male - Image © C. Campbell

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Male Phanaeus sp.
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