In war on weeds, the Bug Lady bets on hungry weevils
Seattle Times staff reporter
King County's top 4 noxious weeds
According to the county's Noxious Weed Control Board, these weeds are the worst of the worst:
Tansy ragwort: Toxic to horses, cattle, sheep, livestock and people. The toxin is cumulative over the life of an animal, causing decreased liver function. Can reach 4 feet in height, producing bright-yellow, daisylike flower heads. Found in pastures, roadsides and other open areas.
Giant hogweed: A public-health hazard. Its sap can cause severe blistering and sometimes permanent scarring of the skin. Invades native forests and degrades habitat. Can grow to 15 feet, producing large, flat-topped, umbrella-shaped white flower clusters. Found in vacant lots, ornamental gardens, stream banks and ravines.
Spotted knapweed: Crowds out native plants, increasing erosion and reducing wildlife and livestock forage. Produces purple flower and is commonly seen along state highways, railroads and abandoned pastures.
Purple loosestrife: Aggressively spreads in wetland and shoreline areas, crowding out native plants and reducing habitat for wildlife. It grows to 9 feet in height, topped by showy, magenta flower spikes.
QUILCENE, Jefferson County — The weevils had traveled a long way to do their job — more than 300 miles from where they had hatched in an Eastern Washington meadow to their new home in Olympic Peninsula pastures.
Jennifer Andreas — the Bug Lady, as friends sometimes call the entomologist for Washington State University's King County Extension — carefully poured out 500 weevils from one of the cardboard canisters in her backpack.
The imported weevils were being deployed in the battle against another import, the meadow knapweed, a plant with a beautiful purplish-pink flower and an ugly habit of ruining pasture land.
Historically, weeds, causing billions of dollars in damage, have been fought with a variety of methods, including applying pesticides, mowing them down or by simply yanking them out of the ground.
But more and more, government agencies are including another method: bringing in natural predators, such as the weevils.
The little gray-black bugs, which are part of the beetle family, are about a quarter-inch long and certainly didn't appear terribly fearsome as they huddled together.
They love to nibble on knapweed. Andreas looked at them with pride.
"I'm kind of partial to them. I like the snout on weevils. I like the way they lumber along, but then they can get up and fly. I like the way they play dead," Andreas said, referring to these beetles' instinct to fold their legs when sensing a predator. "They're much nicer to work with than flies."
Many of the 111 plants on King County's list of noxious weeds — like the meadow knapweed — would make gorgeous bouquets. Some were originally brought into the country by gardening enthusiasts who couldn't foresee the consequences: The ecology of large swaths of land in America has been turned upside down. The damage ranges from weeds that are poisonous to horses to weeds that produce toxins that decrease growth in agricultural crops to weeds that endanger wildlife as they block out sunlight that provides heat and light in forest understories.
In the case of meadow knapweed, it has a bitter taste that makes livestock avoid pastures that have it.
The knapweed, which comes in more than half-a-dozen species, is among the 1,400 non-native weeds that a 1998 federal interagency report concluded have created "a biological wildfire" in America by crowding out the local vegetation. The report called their unrelenting spread a "silent invasion."
"Very few people appreciate how serious the problem is. It's not like these plants are biting you like a mosquito," said professor David Pimentel of Cornell University's College of Agriculture and Life Sciences, who headed a study that put numbers on the size of the invasion.
"But if you're driving along an interstate highway and get out of the car to look at the plants, the odds are very high you'll be seeing invasive species. The edges of roads are disturbed areas, and that's where a lot of these plants first invade."
The non-native weeds, said Pimentel, have invaded 40 percent to 50 percent of America's croplands, pasturelands and public lands. And they just keep spreading at a rate of 1.75 million acres a year, causing $50 billion annually in environmental and agricultural damage.
An army in the fridge
Last year, Andreas, 30, was hired as the coordinator for WSU's weed biocontrol program in Western Washington. That means she's the one gathering and bringing weed-fighting bugs to weed-control agencies in 19 counties. In 2005, she collected 43,000 insects — 15 different kinds of flies, moths and beetles.
"See them? They're starting to move!" Andreas said, taking out a digital camera. "I gotta get a picture!"
She's unabashedly enthusiastic about bugs. Until she dispersed the weevils, she had kept 40 containers with some 10,000 of the bugs in the refrigerator of the condominium she shares with her boyfriend.
"I think he wishes we had another refrigerator," she said.
On the Olympic Peninsula where she released the weevils, a number of them had begun climbing up the stalk of a plant.
If they live up to their name as seedhead weevils (their scientific name is Larinus obtusus), they'll mate and lay their eggs in the knapweed flowers. Then, their offspring will gorge on the seeds in the flowers.
Three or four summers from now, Andreas hopes to witness their accomplishments: fewer knapweeds because of fewer seeds germinating.
"We have to be patient and accept this is not a quick result," she said.
But, Andreas said, this method is probably cheaper in the long run.
The little critters are given free to counties that want them. The bugs, she said, would be particularly useful in large tracts of land that would otherwise require a considerable amount of chemicals.
A few weeks ago, in Eastern Washington, Andreas and a couple of colleagues used canvas nets — sweeping in figure-eight motion through the knapweed plants — to gather the weevils nesting in the flowers.
To separate the weevils from the spiders, ants, dragonflies, bees and plant material that the nets also collected, Andreas used an aspirator, a tube that is used to suck up individual weevils into a vial.
"It's tiring," she said. "It takes some lung power."
The bugs had been introduced a few years ago at a 500-acre meadow in the Conboy Lake National Wildlife Refuge at the base of Mount Adams in Klickitat County.
But the ancestors of these weevils actually had traveled a much longer distance — some 6,000 miles, as they were brought from Romania and the former Yugoslavia to research labs in the U. S.
Eastern and Central Europe is the natural home for meadow knapweeds, where the seedhead weevils, native pathogens and other local insects keep the plants in check. The knapweeds often arrived in the U.S. as seeds, without those localized controls.
About 20 years ago, researchers decided to import European weevils to control the European knapweeds that were already here. They didn't want to accidentally introduce yet one more non-native species whose population would explode.
But extensive testing of the European seedhead weevils on 78 North American plant species showed they only attacked the knapweeds. In 1993, Larinus obtusus was released in five states.
On that recent afternoon on the Olympic Peninsula, Andreas released 3,500 weevils at seven sites, including sites where last year she had released the bugs.
She was happy to see that those bugs had survived the winter. A new generation had emerged.
"God must have an inordinate fondness for beetles. He gave them so much diversity," Andreas said. "There are so many varieties, so many different colors and designs."
It was a sunny day and Andreas bent over to get a closer look at the weevils nestled in the meadow knapweed flowers.
They were doing their job.
They were eating.
Erik Lacitis: 206-464-2237 or email@example.com
Copyright © 2006 The Seattle Times Company