Rainbow Stag Beetle (Phalacrognathus muelleri)
A few days ago I found this rare and beautiful rainforest beetle which is highly sought after by collectors around the world. The rainbow stag beetle pictured below is also known as the Muellers stag beetle and crawled out of my pants while I was sitting at a cafe in Kuranda early one morning. After the initial surprise I realised that I had never seen this kind of beetle before and a friend who was there identified it as a muelleri beetle. I headed home to photograph it and after a few images I let it go, but it wasn’t until I returned to the cafe the next day that I was told how special it is to find one of these.
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Rainbow Stag Beetle (Phalacrognathus muelleri)
Rainbow Stag Beetle (Phalacrognathus muelleri)
Phalacrognathus muelleri is a well-known but poorly documented species. It is also known as the Golden, Rainbow, Magnificent, Mueller’s and King Stag beetle. It is the Largest Australian member of the Lucanidae family. The Rainbow Stag beetle is confined to the rainforests and adjacent wet sclerophyll forests of coastal north-eastern Queensland between Helenvale near Cooktown and the southern end of the Paluma Range.
This most spectacular beetle breeds in rotting wood in both fallen and standing, living or dead trees. The larvae feed on the decaying wood of various species of trees. This decaying matter is usually moderately moist although they can at times be found in relatively dry timber. Adults feed on the same material as the larvae and supplement their diet with plant sap, fruits and nectar from flowers.
Up to 50 eggs are laid by each female. Eggs are deposited singly, but females have been observed to lay up to 30 eggs in a close group. Eggs take from 10 to 14 days to hatch, in which time each egg expands to become almost double it’s original size. The larva is visible within the egg just before emerging. Oviposition occurs throughout the year. Males have been recorded in the company of ovipositing females. The larva constructs a pupal cell, which may take up to a week to complete. At this stage the larva moults and a pupa is formed. The pupa will change position in the cell many times during its development. The pale pupa begins to attain a metallic colour, almost opal like.The soft beetle then emerges with soft white wings that harden and develop their brilliant rainbow colours over a period of one week. The adult may remain with the pupal cell for up to eight months before emerging.
Males can vary in length from 24mm to 70 mm. Females are generally much smaller measuring from 23 mm to 46 mm. Irrespective of individual beetle size, mandibles can vary considerably between males.Adults break out of their pupal cells using their mandibles and jaws. Males with well-developed mandibles use the base of these for chewing while using their tarsi for raking out any excavated material. Upon emerging from the pupal cell an adult will disperse in search of food, mates and an oviposition site. Adults are known to live for up to 18 months in captivity.
Males use their mandibles as levers when in conflict with one another. Two protagonists will approach each other with the mandible lowered. Each beetle tries to pass beneath its opponent’s body or legs, at which point the mandibles are raised in an attempt to dislodge the rival. It is not unusual for the combatants to be thrown into the air or rolled over on their back.
