Beetle mania sweeps Kamiak Butte thistles

Tiny pollen-dusted beetles dig deeply into the yellow flowers of the yellow-star thistle on the south side of Kamiak Butte.

One, two, three, maybe four hairy weevils at a time can collect on a single yellow flower, their main source of food.

Park officials released 11,000 weevils on the southern slopes of Kamiak Butte July 6 in a federally-funded bid to rid the area of yellow-star thistle.

The weevils are a bio-control solution to preserve the native fauna of the 1,000-acre butte, one of the few remaining native areas in Whitman County.

A single hairy weevil clings to the petals of a yellow-star thistle flower atop the south side of Kamiak Butte.

The weevil release is part of a larger program Whitman County Parks is pursuing to preserve the native growth on the butte. Part of the preservation program also includes eliminating unwanted trails and tracks worn by wayward hikers.

Yellow-star thistle is not native to the Palouse prairies and its thick, aggressive growth tends to choke out other plants.

Patches of the plant with its pale blue-green leaves and thorny yellow flowers cover the south side of the butte.

The control weevils only eat yellow-star thistle, with the adults eating the flowers and then laying eggs for larvae that eat the seeds.

“That’s why the bio-control agents are so valuable. They go where the weeds go,” said Park Ranger Justus Barton.

As part of the preservation program for the butte, Barton will this fall go to work filling in unwanted trails by planting native prairie grass and wildflowers in their place.

“There’s supposedly 3,000 linear feet of unintentional trails up here,” Barton said.

Dave Mahan, park ranger at Wawawai, said they have dug up the soil on some of the unintentional trails on Kamiak and planted native prairie grass.

“It took a really long time to germinate. I was biting my nails,” Barton said. The day of a Gazette visit to the butte, July 19, native prairie grass was sprouting in the new trail.

The federal grant behind preserving the butte is a U.S. Fish and Wildlife Prairie Restoration Grant, awarded to the county in 2006 for a lump sum of $25,000. The county is also putting up $6,000 in labor hours.

This year’s batch of weevils was purchased from a Montana bio-control company for approximately $3,200. Weevils use their probosci to pierce a flower and then suck up the resulting pulp.

The yellow-star thistle has dandelion-like flowers which grow on pale green leaves and stalks.

Barton said they are working mainly on the yellow-star thistle on the private property adjoining the butte. He said the county’s land is mostly rid of the thistle. The county owns about 298 acres out of the 1,000 on the butte.

Park staff released the weevils at three different points on the southern side of the butte on private property.

“The yellow star has been pretty much abated on county property,” he said.