An Arlington civic group, sick of the sight of half-eaten flowers, has declared war on a garden pest with expensive taste.

The Japanese beetle, the shiny green and brown bug that prefers to dine on roses and raspberries, has shown up this summer in several areas of the county.

"They like the roses. They've attacked the hydrangea. Now they're starting on the mums. It's sort of a moveable feast," said Sherwin Landfield, who lives on Vacation Lane and tends a garden there.

"The beetles sit on almost any plant I can think of in my yard and eat," said Fran Sawaya, who lives in north Arlington. "You go out and see something you've planted is all eaten up. It's sort of discouraging."

Landfield and other members of the Donaldson Run Civic Association are mounting a plan to rid the neighborhood of the beetles.

Maggie Chadwick, co-president of the association, said the civic group has made arrangements with a firm to treat neighborhood yards this fall. Civic group members and nearby residents interested in receiving treatment will need to pay $20.

Carol Bruce, an urban technician for the Arlington office of the Virginia Extension Service, said that Arlington was treated for Japanese beetles about 25 years ago by the U.S. Department of Agriculture. The treatment, a product called Milky Spore that is applied to the ground, appears to have a life span of about 20 years, she said. Bruce said the treatment has begun to wear off.

"We started to see a really big population last year," Bruce said. She said the extension service has received calls from Arlington residents again this summer complaining that the beetles are back.

"Roses, fruit trees, bush berries. Those are probably some of their favorite foods," she said. "They seem to favor the kinds of things that are treasured by gardeners.

"They like to breed," Bruce added. "They're large and so they can eat a lot. They're built like little tanks and they're fairly impervious to insecticides."

Fred Wood, a former president of the civic group, said he feels the county should pick up the tab.

"I think the Japanese beetle can have substantial destructive impact," Wood said. "It's not as dramatic as the gypsy moth. But my feeling is that the county is very well off . . . and the county should be able to take on both problems. At the rate things are going, not a whole lot of neighborhood groups are going to get their act together to do something about it. The problem is going to get worse."

But Arlington officials, who have advised county residents to fight the beetle problem in the same way the Donaldson Run civic group is fighting it, say Japanese beetles do not pose the same kind of significant threat that gypsy moths do. In addition, beetles are both more expensive and more difficult to exterminate.

"Japanese beetles are not as destructive as gyspy moths," said Elizabeth Montgomery, an agent with the extension service. "Certainly a 200-year-old tree is harder to replace than a rosebush".

Fred Louis, chief of the Arlington Park Division, said that treating the county for beetles would be prohibitively expensive. The county spent about $17,000 during the last fiscal year to spray roughly an eighth of the county for gyspy moths, he said.

Louis said county officials have estimated that it would cost between $150,000 and $200,000 to treat the county for beetles.