This beetle’s misplaced affection has deadly consequences
Risking life, limb, and genitalia, jewel beetles looking for the perfect partner mistakenly mate with bottles.
This story appears in the April 2021 issue of National Geographic magazine.
It was springtime near Dongara, in Western Australia, and biologists Darryl Gwynne and David Rentz were conducting field research on insect species. At one spot by the road was a discarded beer bottle—the squat variety known in Australia as a stubbie, with bands of small bumps adorning its brown glass. And clinging to the empty bottle was an insect: a member of the jewel beetle family bent on copulation, attempting to insert its sexual organ into the bottle.
Since Gwynne and Rentz witnessed that in 1981, other observers have documented the behavior on social media. It’s identified as an example of supernormal stimuli, in which a stimulus elicits an exaggerated response. In this case, the provocateur is the stubbie: The male beetle apparently mistakes the bottle for a giant female of its species, which has similar coloring and bumps on its shell. Males lose not only their minds for this gleaming love goddess but sometimes their lives. A beetle feverishly mounting the bottle can be attacked by ants that, in the words of Gwynne and Rentz, may bite into “the soft portions of his everted genitalia.”
For this discovery the biologists received an Ig Nobel Prize, the tongue-in-cheek award that recognizes scientific research projects that “make you laugh, then think.”
The jewel beetle inhabits arid and semiarid zones of Australia, in the states of Queensland, New South Wales, South Australia, and Western Australia.
The jewel beetle family Buprestidae comprises some 15,000 species, including an estimated 1,500 found in Australia. The one Gwynne and Rentz studied is from the genus Julodimorpha; its species designation remains a matter of debate. The beetles can grow to more than an inch and a half long, and females are larger than males. The male jewel beetles can fly, but the females can’t.