By fall, homeowners in the Twin Cities metro will officially face a new six-legged threat: termites.

At least that's the assessment of the U.S. Department of Housing and Urban Development, which has deemed the southern half of the state as being at "slight to moderate risk" for highly destructive subterranean termites.

That assessment, a shift for the agency, means that in September new houses financed with government-backed mortgages will have to comply with federal rules aimed at preventing the kind of expensive and damaging infestations that are commonplace elsewhere in the country.

For years, Minnesota was exempt from those codes, but that was an "oversight" that's being corrected with publication of a new guidebook of rules that's being sent to lenders, according to HUD spokesman Brian Sullivan.

Though the change is aimed at preventing expensive and destructive termite infestations that are commonplace elsewhere, pest experts and building ­officials say such measures are ­unnecessary.

"This is ridiculous overkill," said Jay Bruesch, technical director for Plunkett's Pest Control in the Twin Cities.

Bruesch said that his company is often asked to do post-construction termite inspections and prevention work for commercial buildings and sometimes for home buyers who are working with corporate relocation companies that are accustomed to dealing with termite problems elsewhere in the United States.

"And we're a little embarrassed by them because we'll take someone's money for preventing a pest that isn't here," he said.

HUD made the change during a recent update of its regulations that was aimed at simplifying its lender requirements. Local experts say the region should never have been on the list in the first place. Though termites can be a problem in some parts of extreme southern Minnesota, they haven't been a nuisance in the 13-county metro area.

Jeffrey Hahn, an entomologist at the University of Minnesota, said he didn't receive any calls about termites last year.

"Those calls are pretty rare for me," he said. "There's no reason to believe they're any worse now than they were 10 to 20 years ago."

Subterranean termites do occur naturally in parts of Minnesota, but are rare, and contrary to conventional wisdom are capable of surviving a Minnesota winter by nesting below the frost line.

They're also capable of hitchhiking in lumber on rail cars, for example, to reach here from more termite-friendly areas. Hahn cites the recent case of a Twin Cities woman who discovered a termite infestation in her sofa, which was made more than a decade earlier in the southern U.S.

Experts say that while homeowners in the Twin Cities face plenty of threats, including carpenter ants, termites aren't among them.

"As far as pests go, in my 23-year career, I have seen dozens of squirrel, raccoon, mice, bat, and bird problems, but never termites," said Keenan Raverty, immediate past president and chairman for the Minnesota Mortgage Association. Raverty said that his organization wasn't notified of the upcoming change. He added that some underwriters who aren't familiar with conditions in the Twin Cities have asked for documentation showing that a building site was pretreated.

Currently, there's no inspection requirement involving termites for existing homes anywhere in Minnesota unless there's evidence of a problem.

Bruesch said a simple inspection of an existing home can cost as little as $98, but he estimated that fully pretreating a house before it's built can cost upward of $1,000.

The Twin Cities metro area and other southern Minnesota counties were taken off the exception list after recommendations from a Washington D.C.-based pest control trade group. The HUD rule on termite prevention applies to new houses purchased using FHA and other government-backed financing.

Andrew Bray, director of regulatory affairs at the National Pest Management Association, said the organization has been advising HUD on best practices. Rather than using an old USDA map that simply had a line that cut through the center of the state, Bray said, the association recommended listing specific counties where there was a threat.

Across the state, many new houses already meet the requirements because the building code requires pressure-treated lumber in areas that are vulnerable to rot, which is appetizing to termites. Other options for prevention, according to the HUD rules, include spraying the site with termiticides or using a baiting system.

The change comes at a challenging time for Twin Cities-area builders, who are already adapting to recent code changes and a new suite of regulations, including an mandate that they include whole-house fire sprinklers in houses with more than 3,000 square feet.

Remi Stone, executive vice president of the Builders Association of Minnesota (BAM), said the organization wasn't contacted about the changes. She said she worries that some lenders, builders and buyers will be surprised by the additional documentation that will be required.

"BAM is frustrated when an industry peer, such as HUD, overlooks communicating with the very industry it impacts when issuing amended guidance on disclosure matters important to Minnesota's home buyers, especially when that something is sensational as termites," she said. "Buyers and builders deserve a little more heads up on things like this."