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Most gardeners will tell you weevils are bad news. But on Friday morning, volunteers worked to release tens of thousands of the insects on the Jordan River Parkway Trail.

This particular variety of weevil feeds on one plant, and one plant only: the notoriously thorny weed known as goathead or puncturevine. The Jordan River Parkway Trail has been infested by the weed to such an extent that the puncturevines are driving away cyclists and other would-be trail users, prompting the Jordan River Commission to turn to the weevil for help.

"We got a lot of complaints from users of the trail that you would get four flat tires every time you go," said Laura Hanson, executive director of the Jordan River Commission.

Hanson said her organization first heard of the weevil several years ago, when someone recommended the insects after their success in controlling puncturevines in other parts of the U.S. But the weevil couldn't survive Utah's winters, so it hadn't yet been deployed here, she said.

For the past four years, the Jordan River Commission and volunteers have released tens of thousands of weevils — about 25,000 insects this year — on the most puncturevine-infested parts of the trail.

Hanson acknowledges it isn't the most inexpensive solution. One carton of about 250 insects goes for $80 — an expense the Jordan River Commission covers via a grant from the Utah Department of Agriculture and Food. But Hanson believes the weevils have been effective, and they reduce the need to use herbicides, which she said have a negative impact on the river environment.

Puncturevine is an invasive species in Utah, Hanson said, native to the region of the Mediterranean Sea. She said scientists believe the vine came to the U.S. as stowaways in the fleece of sheep, and, in the absence of their natural predators, quickly flourished.

The commission plans to continue releasing the weevil each summer until that area's infestation is reduced to the point that it can be controlled by volunteers and gardeners armed with spades and gloves. Meanwhile, she said, interested residents can adopt a weevil for 50 cents by visiting the commission's website.

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