ST. FRANCIS, Maine — One of the first things Mary Landry and her husband did this summer was paint their deck, which overlooks the St. John River, something they hadn’t considered doing for years.

“We finally had a summer we could enjoy being outside,” Landry said early last week. “It was so great, until about two weeks ago.”

That was when the flies that plagued residents the previous six summers arrived, driving homeowners along a 10-mile stretch of Route 161 west of the Fort Kent-St. Francis town line back inside.

“They are back with a vengeance,” Landry said. “All summer … we’d see only a single fly here and there and joke about it.”

No one is joking now.

Since 2007, hordes of what are believed to be houseflies have swarmed outdoor gatherings from family reunions to community barbecues all summer long, according to residents.

“We really started seeing it in 2007,” Landry told the Bangor Daily News last summer. “We had a family reunion and put the food in the garage, and that food was immediately covered in flies. It’s been getting worse ever since.”

From the outset of the problem, St. Francis residents pointed to poultry operations across the St. John River in Saint Francois and Connors, New Brunswick, as the source of the flies.

Numerous phone calls and emails were exchanged for years between residents and officials with the Maine Department of Environmental Protection and the Maine Department of Agriculture, Conservation and Forestry. While sympathetic to the homeowners’ plight, the departments faced jurisdictional issues because of the international border.

Those officials last summer did inspect possible fly sources on the Maine side of the border and reached out to their Canadian counterparts to check possible trouble spots in New Brunswick.

“Last season staff visited the area when advised of the situation,” Valerie Kilfoil, director of communications for the New Brunswick Department of Agriculture, Aquaculture and Fisheries, said in an email last week. “Following that visit, staff worked to increase the level of awareness among producers concerning the fly issue in the area and provided suggestions on dealing with production sites that may be contributing to the issue.”

No specific poultry operation has been identified as the source of the flies.

On Friday, the mayor of Saint Francois, New Brunswick, Gerard Cyr, said he had not received any complaints from his constituents regarding fly issues. He also said he was not aware of any poultry manure-spreading operations taking place in the area.

“Our poultry specialist visited the area on both the New Brunswick and Maine sides earlier this summer, and there was no evidence of any issues with flies,” Kilfoil said. “To date, neither our department, the department of environment [or] local government have received any complaints from the area.”

While they may not be complaining through official channels, residents across the river in St. Francis are far from happy.

“We spent all summer with no flies,” Karen Gagnon said. “We didn’t even know where our fly swatter was.”

Then two weeks ago, she and her husband were looking for that fly swatter and were hanging rolls of sticky fly-tape when the flies reappeared.

“We brought in firewood last week, and the basement was right full of flies,” Karen Gagnon said, adding the hours between 5 and 7 p.m. are the worst.

“We are vacuuming them off our screens every evening,” she said. “The screens are black with flies.”

In his woodworking shop, Robert Gagnon pointed to a dozen strips of fly tape he’d hung the previous day. Each was covered with flies.

“That’s just in 24 hours,” he said. “As soon as the sun comes out and the air heats up, they are everywhere.”

Up the road at the Store on Sugar Shack Road, employees say they can’t keep fly tape on the shelf. As of mid-week, the tape was sold out again.

All this was news to state environmental and agriculture officials.

“We have not heard a peep from either side,” Nick Archer, regional director for Maine DEP at the agency’s Presque Isle office, said Friday. “I was actually up there not more than three weeks ago and went through Saint Francis, and there was not a sign of any flies.”

Now that the issue seems to have returned, Archer said he is ready to react with his colleagues in Augusta and their counterparts in Canada, once Saint Francis residents contact them.

“We do have a chain of protocol to follow,” he said.

Among those in that chain is Matthew Randall, compliance officer with the Maine Department of Agriculture, Conservation and Forestry, who was involved with the fly problem last year.

“To be honest, I was in disbelief to hear it was a problem again because things have been so quiet,” Randall said Friday. “This is the first time we have heard of a problem this year, [and] it looks like we almost made it.”

Randall said he has no idea what may have changed two weeks ago to bring back the flies, adding it could be anything from fluctuations in the weather to different agricultural practices.

“We don’t know for sure what has gone on,” he said. “We don’t want to point fingers, [but] our strongest suspicions are it is coming from across the border and our research to date points that way as well.”

Looking for sources and solutions across the St. John River brings jurisdictional issues into play, Randall said.

“We don’t have any jurisdiction in Canada,” he said. “We have communicated with our counterparts on the other side and let them know what we are hearing.”

The process, he said, becomes something of a balancing act.

“Everything needs to be based on fact and due diligence,” Randall said. “We have to rely heavily on the Canadians’ continued efforts and cooperation, which to date have been very good.”

Everyone involved, Randall said, has the same goal of eliminating the problem.

“Last year we worked hard on this issue,” he said. “Everybody wants to be part of solution, and none of us want to see these people suffering.”

That being said, Randall added any action taken by his office is “complaint driven” and residents need to contact him.

“They need to call or email us,” he said. “I wish we had known this two weeks ago when it started up again.”

As was the case last year, cooler temperatures and winter will knock the flies back for another season. But Randall said he does not want a repeat of the fly invasion next year.

“The best route is prevention, and we were certainly working on that before and will now be working on it again,” he said. “We don’t want things to be simply better; we want things to be great.”

Julia Bayly is a reporter at the Bangor Daily News with a regular bi-weekly column. Julia has been a freelance travel writer/photographer since 2000.