By: Chris Hosking, Category: At The Museum, Date: 22 Jun 2014
For the past few years the Australian Museum has bred this amazing beetle. This has required trying new ideas and a few little changes.
The Egyptian Beetle, Blaps polychresta, has been on live display for more than ten years at the Australian Museum. They are an active, long-lived, medium-sized Beetle which can be easily maintained in captivity. They are different from other beetles that are available in captivity since they are large enough to be easily seen and are exotic to Australia. The species naturally occurs in Egypt and Syria and was introduced to South Australia in 1830. It is now established in the wheat growing regions of South Australia and Victoria. . The natural diet is actually rodent droppings, so although they are introduced they are not a pest as long as rodents are controlled.
In captivity they thrive on chopped apple and carrot as well as ‘Orthopteran Mix’.
Orthopteran Mix is an artificial mixture, developed by entomologist Dr David Rentz. Which is fed to captive cockroaches, crickets, katydids, grasshoppers and some beetles.
Orthopteran Mix recipe used at the Australian Museum:
• 1 cup rolled oats
• ½ cup small parrot seed
• ½ koi pellets
• 1 cup fish flakes
• 1 teaspoon vitamin powder
• 1 teaspoon calcium carbonate powder
Mix all ingredients together then blend until it forms a fine crumble. One teaspoon is fed twice a week on a small dish. The grubs feed on the same mixture which is burried under 3-5mm.
Until 2010, very few Egyptian Beetles had been bred at the Museum. The species is easy to collect in the wheat growing regions of South Australia and Victoria which share a Mediterranean climate similar to their native homeland. However, without breeding our own beetles we are reliant on animals being sent from interstate, which can be costly and is not always possible.
This species mates readily (and often) in captivity and small larvae were observed in the substrate, indicating that egg laying was occurring. Given these two factors, it was decided that the problem was the grubs being able to progress to the next life stage (pupae) and eventually emerge as adult beetles.
It was decided to sieve out the larvae (every three to four months) and place them in an off-exhibit enclosure. By being away from the public it illuminated any chance of high noise and vibrations which may be impacting the animal’s development. Another change was to increase the depth of the substrate (fine red and white sand) to 15cm. Water was provided daily by spraying one side of the enclosure in order to provide a moisture-gradient (the same as the beetles on exhibit) this allows the animals to choose the best level of moisture to pupate in. Food (Orthopteran mix) is buried under 3-5mm of substrate on the dry side for grubs to feed from.
The breeding of this species demonstarted the importance of considering all stages of the animal's life cycle when trying to raise healthy sustainable populations. The breeding success mentioned above is a result of keeping the grubs in deep (minimum 15cm) soil with a moisture gradient in an off display area free of disturbance. In May 2014 the population of 14 adult beetles was divided into two groups of seven, one in the off-exhibit mentioned above. The second group is on display in the Museum's enquiry centre; Search & Discover. These groups are swapped over every few months to prevent stress and continue the sucessful breeding program.