They smell like sweet meat, destroy vacuum cleaners and are wreaking havoc across rural New Zealand.

An unusually wet summer has brought joy to farmers and grief to residents, as a plague of cluster flies descends on homes in the Canterbury and Wairarapa regions.

Cluster flies – which are larger, more sluggish and smellier than a common housefly – pose no risk to human health but can come as an unwelcome surprise to those whose houses they cluster in.

One homeowner in Masterton told Stuff that it was the worst season for cluster flies in her 20 years living in the area, and that she needed to run multiple vacuum cleaners in multiple rooms twice a day just to clear the onslaught.

Rural New Zealand homes overwhelmed by smelly cluster flies – video

“At times it was so disheartening when you vacuum in the morning and by the evening they are back again,” said Lisa Urbani. “You feel like you’re fighting a losing battle. Once or twice I felt quite depressed about it all. I thought ‘Oh my God, will it ever end?’”

The infestation has meant good business for pest control workers, who have been swamped with requests for help.

Daniel Highman​​ of Guaranteed Pest Control in north Canterbury has been working from dawn until dusk for weeks, and has needed to rope in his partner to keep up with demand.

“My alarm clock is basically my phone ringing in the mornings with clients in need of cluster eradication,” he said. “It’s been absolutely crazy.”

Highman has never seen cluster flies in such numbers since starting in the industry six years ago. “Reports I’ve had from farmers who have farmed in the district for longer than I’ve been alive say they have never seen them this bad ever,” he said.

A bug expert warned that scenes like those might become more common as climate change gave insects longer breeding seasons.

“Insects like it when it’s warm and they also like it when it’s moist,” said entomologist Dr Paul Craddock. “When you’re seeing longer, warmer summer months, that means numbers may build up in certain years, and start coming into contact with people.”

Patricia Hilton of Allpest Pest Management in Central Otago said she couldn’t help but be impressed by the flying critters after a decade of working with them.

“They’re so clever. They’re so sneaky,” she said. “They hang out in summer time just doing their fly thing. Then when it cools down they come inside and give off a sweet, meaty smelling pheromone, so they [other flies] know it’s somewhere safe to hibernate for the winter.

“In the springtime, they leave the building and mate, laying their eggs in the soil. Then they hatch and hang out and have a lovely summer, and it all happens again.”

Source: The Guardian