There's something particularly cruel in using beauty to kill, but that's exactly what scientists at the Chicago Botanic Garden set out to do earlier this summer in the sand dunes of northern Wisconsin. There Kayri Havens and her colleagues planted about 60 3-D-printed flowers to lure invasive weevils to their death.

For more than a decade, beginning in the 1990s, scientists deliberately distributed the invasive weevil Larinus planus throughout the country to consume Canada thistle, an aggressive weed that had run rampant through American farm fields and rangeland. But like many well-intentioned species-control efforts before it, the plan went awry. The long-snouted insect jumped host and attacked native thistles, including the Pitcher's thistle, a flowering spiky plant that grows only in the Great Lakes region and was listed as a threatened species in 1988 by the U.S. Fish and Wildlife Service in response to habitat destruction. Left to its own devices, the seed-eating weevil could cut the Pitcher thistle's possible time to extinction in half, Havens says.

She now hopes the 3-D-printed thistle fakes will come to control the biocontrols. The plastic purple, blue or white flowers—some halfway open, others in full bloom—sit atop 20-inch-long dowels alongside the real things on Wisconsin's Door County peninsula. Most are outfitted with cotton wicks saturated in a lemony or wintergreen scent, both known to attract weevils. “We needed a chemical signature that weevils go crazy over,” says botanist Pati Vitt. Video cameras currently capture faunal activity at the faux-studded floral plots so researchers can catalogue which models the weevils favor, the number of insects that visit and how long they stay. Once the scientists discern the shape, color and smell combo that attracts the weevils—but not bees and other pollinators—a trap will be designed. It could take a few years to determine all the particulars, so for now the weevils that take a shine to the 3-D-printed blooms are captured by hand when possible and thrown in soapy water to die. If the counterfeit scheme works, fields of 3-D-printed flowers might one day stand guard over Wisconsin's dunes.

More 3-D-printed Fakes

DECOY INSECTS

Pennsylvania State University entomologists have set out to kill emerald ash borers, a tiny beetle that destroys ash trees, with electrified 3-D-printed duplicates. When (real) male ash borers land on (fake) females in hopes of mating, the six-legged lotharios receive a fatal shock.

WILDFLOWERS

Plastic flowers printed in an array of shapes are helping researchers at the University of Washington tease out how pollinators, such as the hummingbirdlike hawk moth, pick certain blossoms for feeding.

MOCK EGGS

Cowbirds, which get other birds to raise their young, often lay their eggs in robin nests. The robins have a decent “not mine” meter, however, and frequently cast out the foreign ova. To determine which characteristics tip the moms off, Hunter College ornithologists snuck a variety of 3-D-printed eggs into robin nests. They discovered that intruders are identified by color. —Kat Long and Sarah Lewin