They smell like sweet meat, destroy vacuum cleaners and wreak havoc in rural New Zealand.
An unusually wet summer has brought joy to farmers and sadness to residents as a plague of grape flies descends on homes in the Canterbury and Wairarapa regions.
Grape flies — which are larger, sluggish, and smellier than a common housefly — pose no risk to human health, but can pose an unwelcome surprise to those in whose homes they congregate.
A homeowner in Masterton said stuff that it was the worst season for grape flies in the 20 years she’d lived in the area, and that she had to run multiple vacuums in multiple rooms twice a day just to stave off the onslaught.
“Sometimes it was so daunting when you’re cleaning in the morning and you’re back in the evening,” says Lisa Urbani. “You feel like you’re fighting a losing battle. Once or twice I felt quite depressed about all of this. I was like, ‘Oh my god, will it ever end?’”
The infestation spelled good business for pest controllers, who were inundated with requests for help.
Daniel Highman, of Guaranteed Pest Control in north Canterbury, has been working morning to night for weeks and has had to enlist his partner to keep up with demand.
“My alarm clock is basically my phone ringing in the morning with clients who need cluster eradication,” he said. “It was absolutely insane.”
Highman hasn’t seen so many grape flies since he started in the business six years ago. “Reports I have received from farmers who have farmed in the district longer than I have lived say they have never seen them look so bad,” he said.
One insect expert warned that scenes like this could become more common as climate change means insects have longer breeding seasons.
“Insects like it when it’s warm, and they like it when it’s humid, too,” said entomologist Dr. Paul Craddock. “If you’re seeing longer, warmer summer months, that means numbers can increase in certain years and come out with people.”
Patricia Hilton of Allpest Pest Management in Central Otago said she couldn’t help but be impressed by the flying critters after working with them for a decade.
“You are so smart. They’re so sneaky,” she said. “They hang out in the summer and just do their flying thing. Then, when it cools down, they come in and release a sweet, meat-smelling pheromone, so they [other flies] know it’s a safe place to hibernate.
“In spring they leave the building, mate and lay their eggs in the ground. Then they hatch and hang around and have a nice summer and it all repeats.”