Beetles Battle With Weed

Sun., Aug. 1, 1999

Staff

Oregon Wildlife officials are hoping a hairy beetle will help take a bite out of the yellow starthistle, a prickly weed that’s edging out native grasses from their normal habitat throughout dryland regions of Oregon, Idaho and Washington.

The weed has already shown signs of harming wildlife ranging from chukar partridge to bighorn sheep in the Snake and Grande Ronde river canyons.

“It’s happening slowly, but I’m starting to see small areas where there are not as many starthistles as there used to be,” said Barbara Mumblo, a botanist for the Applegate Ranger District near Medford, Ore., who has been leading the battle against the noxious weed.

The cause of the decrease is the yellow starthistle hairy weevil, which munches on starthistle seeds.

The bugs were let loose on patches of starthistle in southern Oregon four years ago.

“We release a small amount about 100 at each site so it takes a while for the population to build up,” Mumblo said.

What the weevil and the weed have in common is their roots in the Mediterranean region. While starthistle was unintentionally introduced shortly after the turn of the century, the hairy weevils were brought in on purpose to check the invasion.

“Starthistle got over here and didn’t have any predators,” Mumblo said, adding that the hairy weevil was its nemesis back in Greece.

Yellow starthistle offers virtually no forage for wildlife and can be poisonous to livestock.

The hairy weevil isn’t the only biological weapon in the researchers’ arsenal. The yellow starthistle peacock fly, yellow starthistle bud weevil and the yellow starthistle flower weevil are also in the bug battalion.

But it’s still too soon to tell how effective the bugs are in battling the weed. “The seed can last on the ground for 10 years,” she said. “You may not see it for a while, then it can come back. You have to keep watching for it.”

In the meantime, The Nature Conservancy plans to fight the starthistles the old-fashioned way - pulling them by hand.

Prescribed fires on the property also appear to be helping the land regain its natural balance, said botanist Molly Sullivan, Southwest Oregon stewardship coordinator for The Nature Conservancy.

“The trick is you need to be persistent,” she said.

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