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Silence! I kill you!
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Discussion Starter · #1 ·
Here is a pretty neat article I found in the SJ Mercury News. The results won't come quickly, but if they help I'm all for it!

Biologists deployed an unlikely warrior Friday in the battle against an invasive weed that is infesting the hills above Silicon Valley.

It's hairy weevils to the rescue.

Just in on a plane from Montana, 6,000 of the little bugs were released to snack upon bristly yellow star thistle, the bane of valley hikers and ranchers. For bugs hungry after a long flight, it was the insect equivalent of an All-You-Can-Eat buffet.

The weevils are modest creatures best viewed through a magnifying glass. They're brownish-gray with a big proboscis -- think elephant, only smaller -- and they cost 25 cents apiece.

But they are tough on thistle. The yellow star thistle is a rugged, spindly scourge that has spread across the hills and mountainsides of California and other Western states. It is thought to cost millions of dollars in lost grazing land and hay. It also sucks water out of hillsides, making them inhospitable to other plants.

In their native Mediterranean habitat, weevils and thistles live in balance, keeping each other's populations in check, said Midpeninsula Regional Open Space District plant biologist Lisa Infante.

``We're restoring a natural predator,'' she said, opening boxes of bugs.

The hairy weevil lays its eggs inside the thistle's seed head. When its youngsters hatch, the seeds are their first meal. As adults, they eat bugs.

While the bugs are unlikely to completely eradicate the thistle from California's hills, it is hoped that they will reduce populations so that other plants have a chance, she said.

The approach is called biological control. By importing an exotic plant's natural enemies from its country of origin, it offers a safe alternative to pesticides, mowing or burning.

Hundreds of other enemy species of insects have been released in the United States. The best-known example is a beetle used to control a weed called St. John's wort in the 1940s. The beetle reduced the plant to less than 1 percent of its original range, and has kept it there.

The Bay Area's new guests come from Montana, where they were captured by entrepreneurs Noah and Leona Poritz. The couple do a brisk business by driving around in the hills above Bozeman from April to August, collecting more than a dozen species of insects and selling them to places like the Midpeninsula district.

The weevils were chilled and shipped overnight to the Bay Area, packed with ice, in tiny cardboard containers. Then they were delivered, by cooler, to the preserves of Skyline Ridge, St. Joseph's Hill, Rancho San Antonio and Fremont Older.

These bugs are not new to the area. They've been used here before, but this is the largest group to be released at once. Already, the effectiveness of last year's crop can be seen in some of the thistles. Post-weevil, the plant emits a dark stain where it's been damaged. It also does something called ``flagging'' -- where attacked, the stem wilts and no bloom is produced.

After Friday's release, biologist Infante and her assistant Brendan Dolan made a test of the approach. They drape plants in netting, then will compare populations of thistle that have been protected with those that haven't.

Even 6,000 weevils don't go very far in the vast hills of the Bay Area. But it's a start, said Infante. She hopes the newcomers will consort with existing populations of hairy weevils, and multiply.

She isn't worried that the weevils will become a pest on prized roses, or go anywhere they're not welcome. For one thing, they can't fly. They generally like to stay put.

Moreover, they don't eat anything except yellow star thistle.

That's too bad, Infante said, viewing fields full of another new troublesome invader -- Italian thistle. ``No insect eats that.''
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