The Giant Jewel Beetle That Mates With Beer Bottles

A male Australian jewel beetle attempts to mate with a "stubby" beer bottle. Photo: Darryl Gwynne

The story of the giant jewel beetle, Julodimorpha bakewelli, is a love story about a boy and his beer bottle. It's also a story about the impact that human actions can have on another species. Unfortunately, this love story doesn't have a happy Hollywood ending.

But first, a little background on our besotted beetle. Julodimorpha bakewelli inhabits the arid regions of western Australia. As an adult, this buprestid beetle visits Acacia calamifolia flowers. Its larvae live in the roots and trunks of mallee trees, also known as Eucalyptus. Adults can measure over 1.5 inches in length, so Julodimorpha bakewelli is a rather large beetle.

In August and September, male Julodimorpha bakewelli beetles fly over these arid areas, looking for mates. Female Julodimorpha bakewelli beetles are larger than the males, and don't fly. Mating occurs on the ground. This female buprestid has large, shiny brown elytra covered in dimples. A male flying in search of a mate will scan the ground below him, looking for a shiny brown object with a dimpled surface. And therein lies the problem for Julodimorpha bakewelli.

Scattered along the roadsides of western Australia, you'll find the same discarded refuse common along highways everywhere: food containers, cigarette butts, and soda cans. Aussies also toss their stubbies – their word for beer bottles – from car windows as they cross the open expanses where Julodimorpha bakewelli lives and breeds.

Those stubbies lie in the sun, shiny and brown, reflecting light from the ring of dimpled glass near the bottom (a design intended to help humans maintain their grip on the bottled beverage). To the male Julodimorpha bakewelli beetle, a beer bottle lying on the ground looks like the biggest, most beautiful female he has ever seen.

He doesn't waste any time when he sees her. The male immediately mounts the object of his affection, with his genitalia everted and ready for action. Nothing will dissuade him from his lovemaking, not even the opportunistic Iridomyrmex discors ants that will consume him bit by bit as he tries to impregnate the beer bottle. Should an actual Julodimorpha bakewelli female wander by, he will ignore her, remaining faithful to his true love, the stubby lying in the sun. If the ants don't kill him, he will eventually dry up in the sun, still trying his hardest to please his partner.

The Lagunitas Brewing Company of Petaluma, California actually produced a special brew in the 1990's to honor the odd Australian buprestid with a love for beer bottles. A drawing of Julodimorpha bakewelli was featured prominently on the label of its Bug Town Stout, with the tagline Catch the Bug! beneath it.

Though the phenomenon is funny, for sure, it also seriously threatens the survival of Julodimorpha bakewelli. Biologists Darryl Gwynne and David Rentz published a paper in 1983 about the habits of this buprestid species, entitled Beetles on the Bottle: Male Buprestids Mistake Stubbies for Females. Gwynne and Rentz noted that this human interference in the species' mating habits could impact the evolutionary process. While the males were occupied with their beer bottles, the females were ignored.

Gwynne and Rentz were awarded an Ig Nobel Prize for this research paper in 2011. The Ig Noble Prizes are awarded annually by the Annals of Improbable Research, a scientific humor magazine that aims to get people interested in science by putting the spotlight on unusual and imaginative research.