Reap the weevils you sow

2010-08-22T09:00:00Z 2010-08-23T09:36:34Z Reap the weevils you sowBy SEPP JANNOTTA - Staff Reporter Ravalli Republic
August 22, 2010 9:00 am  • 

DARBY - At a casual glance, their posture was telling.

Alongside local students, cardboard cups in hand, a group of folks visiting from Ennis worked a dry, knapweed infested field behind the high school Wednesday, bending and picking.

But their harvest was not berries or table vegetables.

This group stooping under the midday sun was picking ... bugs.

"Most people see us with the cups and they figure we have berries or something," said Seth Garbett, a 2010 graduate of Darby High School who has been helping with a Ravalli County Weed District effort to use these homely bugs, known as root weevils, to combat spotted knapweed. "Then, generally, when people look in our cups, they run. Or start asking questions."

The use of the root weevil to kill knapweed was developed by entomologist Jim Story, who spent much of his career in Corvallis studying these insects and other bio-control agents at the Montana State University Agricultural Research Center.

The root weevil, known in science circles as Cyphocleonus achates, has proven to be the most effective form of bio-control for knapweed, with the larva feeding on the roots before hatching into an adult, all without harming native plant communities.

And, strangely enough, even though control work has greatly reduced the knapweed problem on the valley floor, the Bitterroot has proven to be one of the best places in the state to raise root weevils.

"People from all around the state come to Ravalli County to collect these insects," said Melissa Maggio, the education coordinator with Ravalli County Weed District (RCWD). "We even have people from other states come to collect. I would say we are maybe the most productive insectory in the state of Montana."

On Tuesday, one day before two groups from Ennis arrived in the Bitterroot to pick root weevils, Maggio and a group of Victor and Darby students played host to an "agency collection day."

The project hosts an agency day each week, Maggio said, bringing in government employees from across the state.

On hand this week were employees from Lake and Sweet Grass counties, the city of Helena and the state of Idaho, Maggio said.

And the picking has been good.

The folks from Ennis, a mix of adults and kids, were likely to head home with more than 10,000 weevils, according to Mellissa Newman, who heads up the Madison County Bio-Control Project.

"To get the number of bugs we're wanting we have to come over to the Bitterroot," she said. "Then we can hope to build up our bug population."

Due to a storm that crossed the northern Bitterroot Wednesday, the picking was less productive for a resident collection event in Florence - local landowners are invited to harvest weevils for dispersal on their property.

Nonetheless, Maggio said the nine students and several adults employed by the project were likely to meet last year's total of 130,000 weevils collected.

All the insects that are then turned out into the Bitterroot Valley landscape are typically done so for a donation to the project paid by the landowner, typically $30 to $40 per 100-count container.

Garbett, who applied for the summer job of collecting bio-control insects four years ago, said he has enjoyed learning the science behind the project, but takes additional pride in the economics of the project.

With root weevils selling for more than a dollar each on the open market, he said it's nice to know that the bugs collected help the local land owners save significant amounts of money in their efforts to control noxious weeds.

The inclusion of agencies - they don't have to make a donation - is part of the deal for the Montana Department of Agriculture grant that funds the project, Maggio said.

Over the five years of the project, Maggio said the state has given RCWD close to $20,000 per year to develop its insectory - a small enclosed plot of ground planted with knapweed and sown with root weevils - and disperse the agent throughout the landscape.

The Montana Department of Agriculture gives out grants to bio control programs, mostly involving local schools, using money from its Noxious Weed Trust Fund.

Department of Agriculture State Weed Coordinator Dave Burch said the department typically funds close to $80,000 in grants for bio-control of knapweed.

The height of the effort, money for developing root weevil "insectories" was going to some 10 schools, in addition to the program being run by Story in Corvallis.

This year, Burch said the only school programs it funded were the one in Whitehall, which was the first school to apply for the grant, and the one run by the Ravalli County Weed District.

The difference maker is that these programs have strong involvement from school groups to the point that students often travel to Billings to make the presentation before the grant funding board.

"They eat that up," Burch said.

Maggio said in addition to collecting root weevils and helping make the grant pitch, the students do a lot of other work that benefits the community, from manning a bio-control booth at the Hamilton Farmers' Market and selling native plants to help with revegetation to installing a native garden at Woodside Crossing to helping with the annual floating weed pull run by the district.

"They do a ton of stuff and they really do help us out," Maggio said.

Reporter Sepp Jannotta can be reached at 363-3300 or


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