Bull-headed Dung Beetle

• It is the strongest animal in the world in proportion to its weight: in laboratory tests a male pulled more than eleven hundred times his own mass, the equivalent of a person moving several buses.
• Two types of male coexist: the large, horned ones, which fight for access to the females in the tunnels, and the small, hornless ones, which slip in unnoticed and have proportionally much larger testes.
• Introduced into Australia along with other dung beetles to clear cattle dung, which the local fauna could not process, it solved a serious problem of flies and lost pasture.
• It is the strongest insect ever measured: in tests at Queen Mary University and the University of Western Australia, the most powerful individual pulled 1,141 times its own weight, the equivalent of a 70 kg person dragging 80 tonnes.
• Males come in two morphs: the large ones grow long horns and guard the tunnel entrance by fighting rivals; the small ones grow no horns and go in for sneaking, slipping past or digging side tunnels.
• What decides the morph is not the gene but the food: a male that passes a certain size threshold as a larva grows horns, and one that does not, does not.
• Females sense population density and adjust their offspring's rations accordingly, producing more large males when competition is greater.
• The female packs dung into oval balls at the bottom of the tunnel and lays a single egg in each; the larva develops in isolation inside its ball.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Grassland and dehesa with livestock, in herbivore dung

Gestation / incubation

Development from egg to adult takes 8 to 10 weeks depending on the soil temperature; the whole juvenile cycle takes place inside the brood ball, buried 10 to 15 cm beneath the dung

Litter / clutch size

A single egg per brood ball

Sources consulted: Wikipedia (es): Onthophagus taurus · Dung Beetle Ecosystem Engineers · Cornell CALS · Agriculture Victoria, ficha Onthophagus taurus · Dung Beetle Ecosystem Engineers (Australia) · ficha tecnica de Nueva Zelanda · Ficha tecnica de escarabajos del estiercol de Nueva Zelanda · Agriculture Victoria

Best time: Active from spring to autumn, with at least two generations a year; it overwinters as a fattened larva inside the ball or as an adult in burrows