|Beetle attempts to mate with a beer bottle. Credit: Darryl Gwynne|
Gwynne and Rentz were conducting field work in Western Australia 23 years ago when they noticed something unusual along the side of the road. “We were walking along a dirt road with the usual scattering of beer cans and bottles when we saw about six bottles with beetles on top or crawling up the side. It was clear the beetles were trying to mate with the bottles.”Now that's a great study!
The bottles – stubbies as they are known in Australia – resemble a “super female” jewel beetle, Gwynne says: big and orangey brown in colour, with a slightly dimpled surface near the bottom (designed to prevent the bottle from slipping out of one’s grasp) that reflects light in much the same way as female wing covers. The bottles proved irresistible to males. Ignoring the females, the males mounted or tried to climb up the bottles, refusing to leave. They fried to death in the sun, were eaten by hungry ants or had to be physically removed by the researchers.
Gwynne and Rentz determined that the males were attracted only to stubbies – not to beer cans or wine bottles of a slightly different shade of brown. And it wasn’t the bottles’ contents that captured their attention: “Not only do western Australians never dispose of a beer bottle with beer still in it, but many of the bottles had sand and detritus accumulated over many months,” the research paper notes.