GOOD fences make good neighbors, as the Robert Frost poem goes, but some towns are discovering that the good New England stonewall that gives many communities their character, are too precious to just leave to the neighbors.

That is because the neighbors have been selling the walls, often for thousands of dollars, to stone companies, who then resell them for thousands more to homeowners looking for a classic New England look. Masons can build new walls out of quarried stone, but it is the time-worn patina of lichen-covered walls made of field stone, built by farmers in the 18th and 19th centuries, that have become highly prized.

That stone has become so valuable that walls have been known to disappear during the night, taken by thieves and then sold to unsuspecting homeowners. A sign was recently spotted in Woodstock that read, ''Reward for information leading to the conviction of the person who stole my stonewall.''

So Harwinton, which has lost stonewalls over the years, fought back last month. It passed a law to protect its walls, making it illegal without a permit for anyone to dismantle, demolish, relocate, or bury stonewalls along town-owned roads, even if the walls are on private property. The disappearing New England wall has become such a problem that Ashford, East Haddam, Killingly, New Milford and Waterford are all considering passing similar laws.

''Stonewall theft has really become a huge problem in Killingly, and I think it's definitely time to propose an ordinance like this to the Town Council,'' said Linda Walden, Killingly's director of planning and development. ''No one wants to be the first to do this kind of thing. Now that Harwinton has done it, it's not so daunting.''

The effort to protect the walls has even reached the grass-roots level. The Stone Wall Initiative, a nonprofit group headquartered in Storrs, sent packets to more than 100 communities across the state this month suggesting ways that towns can stop what it calls ''stonewall strip-mining.''

''This is the first time we've ever stuck our necks out into town politics,'' said Robert Thorson, a geology professor at the University of Connecticut who founded the 1,500-member group, which is an affiliate of the Connecticut State Museum of Natural History. ''This bold move by Harwinton is encouraging. It validates a common deep emotion that people have when it comes to protecting these icons of our heritage.''

Many municipalities have designated historic districts or scenic roads where special permits are required to make any changes to properties, but Harwinton's is the first ordinance created specifically for stonewalls, said Harwinton's town attorney, Michael Ryback, who wrote the ordinance at the request of First Selectman Francis Chiaramonte.

''I don't know of any other towns that have done this,'' Mr. Ryback said. ''It's kind of nice to be a trendsetter.''

Such was the sentiment that prompted Janet Burritt of Harwinton to bring the matter to town officials last year.

''I thought we needed something in place, some kind of authority, to stop these guys from tearing down all the stonewalls,'' Ms. Burritt said. ''We're losing our farms and our barns. But stonewalls, they'll last forever if we protect them.''

Under the new ordinance, anyone planning to alter a stonewall along a town road must pay an application fee of $25, and the permit will be granted only if all of several conditions are met, such as proving the work is necessary for safety, and the work will be ''restricted to the minimum amount of stonewall disturbance necessary,'' the ordinance reads. Anyone violating the ordinance will be subject to a $100 fine.

Mr. Chiaramonte said he realized that $100 wasn't that much compared with what homeowners can earn selling their walls, but he felt it was still a deterrent.

''When all is said and done, I don't think most people would choose to go that route,'' he said. ''Knowing that they're breaking the law, and having to battle it out in court is not something most people would do.''

If a permit is granted and a stonewall is dismantled, the property owner is required to submit a survey map of the area and mark the wall's former path with two granite highway monuments, at the beginning and end of the path, which together would typically cost more than $500.

Of Harwinton's 5,300 residents, about 75 attended the town meeting to vote on the stonewall issue, and Gregory Weingart was among a few who spoke against it.

''I think it's unfair that the government can decide how I'm going to landscape my property,'' Mr. Weingart said. ''Next thing you know, they're going to tell me what kinds of shrubs I can and can't plant.''

Mr. Weingart said he recently subdivided a lot and built two houses, something he would not have been able to do after the ordinance was passed.

''Luckily, I did it before the ordinance, or else I would have had to change the lot lines around the stonewalls, and it probably wouldn't have worked,'' he said.

And then there are some in the stone trade who said that wall preservationists are just overly sensitive environmentalists looking for something to complain about.

''This whole stonewall thing is like the new big topic for the tree huggers,'' said Rick Cafrow, owner of New England Weathered Stone in North Windham. ''But they don't realize there's no shortage of stone in New England and there never will be. If this was an endangered species, I wouldn't be doing it.''

Mr. Cafrow was on his cellphone, driving a truck with a sign on back that reads, ''We Buy Stone Walls.'' He was headed to Griswold, where his company was dismantling stonewalls from an old farm to prepare it for a subdivision.

''We specialize in the stonewalls that have to be moved because a developer is coming in with a subdivision and the driveway has to go through,'' Mr. Cafrow said. ''Then there's the homeowner who wants to put something else where the stonewall is, like a pool or a barn, and the stonewall is just a pain in the keister for them. So we take it away and put it to good use where someone else will love it.

''I'm sorry, man, but I'm going to argue this until I'm blue in the face,'' Mr. Cafrow added. ''All those old stonewalls all over Connecticut, lying there, doing nobody any good? You're selfish if you think they should stay there forever.''

Dr. Thorson, who has written books about stonewalls, said it is not the function that is important about the old walls, but the visual reminder they serve of our forbearers and the nostalgic identity they give our region.

''The southwest has its deserts, Minnesota its lakes, northern California its sequoias, New England its stonewalls,'' Dr. Thorson said. ''But our stonewalls are being swallowed up by big yellow machines, loaded onto flatbeds, and rebuilt as ornaments by the nouveau riche somewhere in Fakeville.''

The demand for old, lichen-encrusted fieldstones has become so strong, in fact, that Tim Perkins, a stone wholesaler in Belchertown, Mass., and other dealers have begun sending out bulk mailings in various Connecticut towns asking property owners to sell their walls

''Greetings!'' reads a postcard Mr. Perkins mailed to Ashford residents a few months ago. ''My name is Tim Perkins, owner/operator of Perkins Trucking & Fieldstone Supply. As a stone wholesaler serving masons and landscapers throughout New England, I am interested in purchasing large quantities of stonewalls from your area. Depending on the quality and quantity, your stonewalls could be worth thousands of dollars!''

Suzy Staubach of Ashford said she was ''horrified'' to receive the card.

''I know no one on my street took him up on it, but I'm sure someone in town must have,'' she said. ''I just think old stonewalls are not only beautiful to look at, but they're what makes us different from anywhere else. They should be left alone.''

Mr. Perkins said he never meant to offend anyone.

''First of all, the demand for this stuff is so high, most people are not thinking at all about the walls'' from a salvation standpoint, he said.

''I've been doing this for 10 years and I can tell you, I've probably saved more farms than any of these so-called preservationists because I'm actually paying the farmers for their stone and enabling them to pay their bills.''

Mr. Perkins said he typically pays the property owner $25 a ton for old walls. Masons said they pay around $1,500 to $1,800 for a typical 50-foot stone wall that is 3 feet high and 3 feet wide. Some Connecticut landscapers and masons then charge their customers around $200 a ton, and up to $550 a ton if it is being shipped far beyond New England, like Florida or California.

The demand over old fieldstone has led to escalating incidents of ''stone pirating,'' with antique walls disappearing, little by little.

''At first I thought my wall was shrinking into the ground, then we realize it was thieves,'' said William Hubbell of the wall around his 150-acre farm in Salem.

Stones are also being stolen from the Weir Farm National Historic Site in Wilton, according to the park ranger, Christopher Gezon.

''It's an ongoing problem, and sadly, no one's been caught,'' said Mr. Gezon, who gives walking tours of the site's stonewalls every Sunday.

Josephine Nicholson of East Haddam said she noticed her stonewall dwindling over the past year and recently a giant section of it was taken overnight.

''I want to put an electric zapper on it and fry these guys,'' she said.

In Harwinton, Mr. Chiaramonte, the first selectman, was driving around the 19-square-mile town, pointing out stonewalls and beaming about the ordinance.

''Imagine this place without the stonewalls,'' he said. ''We'd look like Any Town, U.S.A.''

His next mission is to convince legislators to do something at the state level to protect stonewalls along state highways and on some interior property.

''Right now the only thing we have in place for interior stonewalls is in the planning regulations, which basically ask that the stonewalls be considered when subdividing land,'' Mr. Chiaramonte said. ''It's sort of a wish that never comes true. So I'd like to make it a requirement rather than a request, and that might take some authority at the state level.''

State Representative George Wilber, a Democrat of Colebrook, said preserving stonewalls is a nice notion, but he can't imagine it ever selling at the Capitol.

''When the farmers built these stonewalls, believe me, there was nothing romantic about them,'' Mr. Wilber said. ''They were just forever pulling up stones from their fields so the crops could grow, and these 'tossed' walls sort of resulted as a byproduct. I can tell you, as a farmer myself, these stones are never-ending. Every spring, you'd swear the devil is down there pushing them up through the ground.''