Rainbow Stag BeetleScientific Name Phalacrognathus muelleri               

Conservation Status This species has not yet been assessed for the International Union for the Conservation of Nature (IUCN) red list.


The rainbow stag beetle is brightly coloured with a metallic looking back which is coloured with greens, blues and reds. Their mandible and legs are coloured black. They have six legs.

Young are a larva with a segmented body which is white and have a facial patch which is orange.

Males are larger than females. The male measures between 24 and 70mm (0.9-2.8in) while female’s measure 23 to 46mm (0.9 to 1.8in). A range of factors during the development of the larvae lead to the large variation in size. The larger beetles have larger mandibles making them better at fending off other males.


Rainbow stag beetles live for up to 18 months.


The rainbow stag beetle is a herbivore. They feed upon decaying wood as both adults and larvae. As adults they supplement their diet with fruit, sap and nectar.


Australia is the native home of the rainbow stag beetle. Here they are found solely in the rainforests and sclerophyll forests of north-eastern Queensland.


This species can breed throughout the year. A female stag beetle is capable of laying up to 50 eggs which are laid singly. These are laid into rotting wood and hatch after 10 to 14 days. Across this period the egg doubles from the orginal size and the larvae becomes visible.

The rainbow stag beetle spends 2 months as a larva feeding upon the wood in which they were born. They moult three times as a larva before becoming an adult by pupating.

The pupation takes place in a pupal cell which they build over a week. The pupa spends their time developing before emerging by breaking out of the pupal cell using their mandibles. When they emerge their wings are soft and white which take a week to colour up.

From day one they are independent.

It takes four months for the adult to be sexually mature.


This species is able to fly and it is when they do this that they are most often spotted.

Quick facts

The mulleri portion of the scientific name was given to this species by Sir William Macleay who discovered it in honour of Baron Ferdinand von muller who was a botanist with the Victorian government.

Rainbow stag beetles are also known as the magnificent, Mueller’s or king stag beetle.

The rainbow stag beetle is a popular pet both in Australia and oversea’s especially in Japan.