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If you think you have problems with roses in the UK, read on.
Each day, Deb Wolk walks out to the garden of her South Minneapolis home to pick pesky Japanese beetles off her shrub roses.
Wolk, a Hennepin County master gardener, said she is sick of the tiny insects chewing holes through her roses and gnawing at her trees. But even she's stumped on how to get rid of the thousands that have invaded her garden.
"This is the worst year I've ever seen. I'm in awe," she said. "They're devouring anything they can devour."
The Japanese beetle problem in the Twin Cities is worse than ever, experts say. For the past five years, the population has risen steadily, said Jeff Hahn, a University of Minnesota Extension entomologist.
Because the Minnesota Department of Agriculture stopped trapping and surveying Japanese beetles after 2002, there are no good estimates on how extensive the green-shelled pest problem is in the Twin Cities. After finding them in more than 30 counties in 2002, the department considered the pests established in Minnesota, said Bob Koch, a research scientist for the department.
"It just got to be so widespread that the decision was made that the spread of the pest could no longer be slowed down or regulated," Koch said.
Japanese beetles, which first arrived in the Twin Cities in the 1970s, feed on more than 300 plant species, including grass, ornamental plants and trees. They especially like roses, Hahn said.
"If you have roses that you're growing because it's attractive and you like the flowers, you're going to be kind of upset and dismayed that something's chewing it and putting holes in it," he said.
Each June, adult Japanese beetles, about three-eighths of an inch long, emerge from the soil. After feeding on plants, they mate and lay eggs in the soil.
The eggs grow into grubs that feed on roots and hibernate during winter. Those grubs then turn into adults, and next June, the process starts all over again.
The grubs can cause damage, too, Hahn said.
"When they're an immature grub, they feed on the roots of grass and they can actually do injury to the turf," Hahn said. "The potential certainly exists for them to give you a double whammy."
Don't expect to kill Japanese beetles easily, though, said Dr. Vera Krischik, an associate professor of entomology at the U. While there's a variety of treatment options, there's no common, effective treatment that destroys them.
Pesticide sprays will kill adults, but the beetles still will damage plants before they die, she said. Because Japanese beetles are strong fliers, some might fly away and then return after the pesticide breaks down, experts say.
That's the problem Jason Thomas has. Thomas, 38, planted grapes in the yard of his West St. Paul home two years ago. Since then, he has battled Japanese beetles with an insecticide spray he bought from Menards.
"I've sprayed twice so far this year, and I'm seeing them come back already," Thomas said. "I don't know where they're coming from, but they keep coming back."
Most hardware stores sell Japanese beetle sprays and traps. At Jerry's Do It Best Hardware in Edina, store manager Jon Connolly said he sells about 30 to 40 traps and a couple of dozen hose and trigger sprays per day.
"In the last three years, the products have increased in sales about 300 percent," he said.
Hahn urges people to be careful when using traps because they can attract more Japanese beetles than they kill. To kill small adult populations, he said, use soapy water.
Wolk, the master gardener, takes that approach. About three times a day, she plucks the beetles out of her garden and throws them in a quart jar filled with dishwasher liquid. The liquid kills the bugs, and she reuses them as compost.
"I collect about 35 to 40 each time," she said. "They see me coming with my jar, and they kind of hide."
To stop a long-term Japanese beetle problem, experts say, survey gardens or lawns for grubs and treat them with insecticides.
Keller Golf Course in Maplewood has had its course treated twice in the past for Japanese beetle grubs, course superintendent Paul Diegnau said.
The course has had a beetle problem for several years, but at a cost of $80 an acre, treating 40 acres every year is out of the question, Diegnau said.
"Slowly, every two or three years, the populations build, and we knock them back down," he said.
But it hasn't helped this summer.
"They're feeding on darn near every tree on the golf course," Diegnau said.
"Just driving around the golf course, they're hitting you in the face and chest. "I've never seen it like this before."
Adult Japanese beetles will be active through September and die during the winter, Hahn said. But don't expect them to disappear by next summer, he warned.
"If you've seen them this year, you're probably going to see them again next year," Hahn said. "They are here to stay."
Miles Trump can be reached at 651-228-5583.
A STUBBORN PEST
Species name: Popillia japonica
Size: Three-eighths of an inch long
Color: The front of the beetle is dark metallic green. Its wings are tan.
Eats: More than 300 plant species. They especially like roses.
When did it get here? First arrived in New Jersey in 1917, experts say. It came to the Twin Cities in the 1970s.
How do I get rid of them? There's a variety of options but no common, effective treatment. Pesticides can kill adults in the short-term. Experts urge against using traps on adults because they attract more populations than they kill. Using insecticide repeatedly on grubs helps stop population growth.
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