Rainbow Stag Beetle, Phalacrognathus muelleri
Image: Alan Henderson
Source: Museum Victoria
Question: What are these beautiful beetles with huge jaws?
Answer: These beetles are commonly known as stag beetles and belong to the family Lucanidae, of which there are 85 species found in Australia, (with possibly more species still to be described).
Stag beetles lay their eggs in rotten wood with the larvae consuming the wood and the fungus associated with the wood. Suitable timber varies between species from wet rotten logs to moist dead standing timber. Adults of some species feed on nectar, young plant shoots and sap flows but most species are not known to feed as adults.
Males of some species have large mandibles which are used to battle other males for mating rights. Hence the common name of stag beetles in that they use their mandibles in a similar fashion to the way stags use their antlers. The species that is most commonly brought to the Museum by people is what is commonly known as the Golden-green Stag Beetle (Lamprima aurata). While some species in this family are fairly plain in colour, others such as the Rainbow Stag Beetle have spectacular colouration. There are also a number of threatened species of stag beetle in Australia.