Biology

The adult beetle stage of Xylotrupes feeds on the soft bark of young shoots of many trees, a favorite being the Poinciana trees gracing so many of Queensland’s gardens and streets. Sometimes a particular Poinciana tree will become especially attractive to the beetles and large groups of them may be seen festooning its young branches. Minor damage may be caused by the feeding beetles, but it is rare for any permanent damage to occur. It is thought that these gatherings are part of the beetles’ mating behaviour.

As with all beetles, the rhinoceros beetle larvae (grubs) hatch from eggs and develop into pupae, and these eventually emerge as adult beetles. Each female lays about 50 white eggs in decaying vegetable matter and these take about three weeks to hatch. The larvae feed on decomposing vegetable material and are valuable in accelerating its break-down into compost. In New Guinea the larvae reach maturity in about eight months, but in southern Queensland, it is thought that they require two years of growth before reaching full size. The larvae of Xylotrupes are easily recognised by their translucent grey colour, fine reddish down, dark brown head and enormous size - almost filling the palm of a hand. The larvae are most commonly encountered when digging up old compost heaps or tending a well-mulched garden. In the bush, they are abundant in Australian Brush-turkey (Alectura lathami) mounds.

it with faeces that solidify into a waterproof layer. The larva then transforms into a pupa inside the cell. After about a month the adult beetle hatches out and digs its way to the surface. The beetles live for about 2-4 months.