Flies are swarming across Britain in numbers residents describe as unbearable, with towns including Congleton in Cheshire, Llanelli in west Wales and Sileby in Leicestershire reporting infestations so severe that some homeowners are putting their houses up for sale.
In Congleton, more than 1,250 locals have signed a petition urging the council to take action. The petition was launched by 27-year-old mother Francesca Davies, who said: "The flies are more than just an annoyance; they contaminate food and can carry diseases. The toll on our daily lives is tremendous."
One neighbour called the situation "unbearable." Another said: "Imagine never being able to open your doors or windows for more than a few seconds. No eating outside. Every action you take has to be considered in terms of how many flies it'll let into your home." A third resident said her children can no longer play in the garden because of the swarms.
In Llanelli, residents say they are prisoners in their own homes, unable to open a window without dozens of flies rushing in. In Sileby, residents say the infestations make their lives "intolerable." Homeowner Colin Readwin told the BBC last month: "We've had candles going, we've had fly spray, we've been flicking them with dusters and they're buzzing around your head. It's awful."
Why this year is so bad
The heatwave that hit Britain in June, when temperatures reached 37.7C (99.8F) and broke previous records for the month by more than two degrees Celsius, created ideal breeding conditions for flies.
Flies are coldblooded, or "ectotherms," meaning they cannot regulate their own body temperature. They are sluggish in winter but highly active in hot weather, when their metabolisms speed up and larvae develop into adults in under a week, accelerating the breeding cycle.
Wasps, one of the most effective predators of flies, have also been hit by this year's unusual weather. Wasp numbers are down because of intense wet weather in spring followed by late frosts in May that killed off many wasp queens. The heatwaves that followed dried up flowers, cutting off the wasps' nectar supply.
Wasps are apex predators among insects, and even their larvae are carnivorous. Without them, flies multiply unchecked. Flies can mate on their first day of adult life, live for up to a month, and females can lay up to 100 eggs in a single batch within two days of mating, repeating the process several times in a lifetime.
A genuine health hazard
The common house fly carries so many germs that in Australia it is known as a "filth fly." Its feet and body pick up particles from anything it touches, from faeces to rotting animal carcases, which flies also use as beds for laying eggs.
When a fly lands on food, it regurgitates a toxic sludge rich in bacteria that helps break the food down before it is sucked into the fly's gut. Flies also excrete frequently, meaning food they land on briefly can be contaminated with vomit and faeces as well as matter picked up elsewhere.
Flies spread diseases and infections including salmonella and E. coli, as well as bacteria increasingly resistant to antibiotics, such as some strains of staphylococcus. A 2023 study for the US National Library of Medicine warned that as gregarious and indiscriminate feeders, house flies bridge the gap between filth or other sources of bacteria, such as manure, feed waste and sick animals, and areas of human habitation.
What actually works
Dr Cameron Webb, a clinical lecturer at Sydney Medical School, said an old-school fly swat "works a treat." Locals in Llanelli have also posted pictures of flypaper strips coated with hundreds of trapped flies; ten rolls can be bought online for less than a fiver, and they work by attracting insects with a sweet scent before trapping them on the sticky surface.
But killing flies does not solve the underlying problem, and by the time one is swatted it may already have transferred microbes to a kitchen surface. A few other methods can help. An electric fan creates strong air currents that make it hard for flies to settle, keeping them away from food even if it will not keep them out of the kitchen entirely.
Flies hate the smell of coffee, which biologists suspect confuses their sensitive odour receptors, and they also avoid smoke out of an instinct to stay away from fire. One remedy combines both: heating a couple of scoops of used coffee grounds on a baking tray in a hot oven for 15 minutes, then leaving the smouldering tray on a heatproof worktop. The fumes can keep flies away for around three hours, even with doors and windows open.
Roasted cinnamon on the stove is another effective repellent, though it leaves a home smelling like Christmas in midsummer. Boiled orange and lemon peel release limonene, a scent flies dislike, and lavender works too because of its high linalool content, a compound also found in mint and citrus plants.
Those without a garden or window box can mix a dozen drops of lavender essential oil with a teaspoon of witch hazel in a spray bottle of water. Alternatively, drops of eucalyptus or peppermint oil added to white wine vinegar and sprayed around doors, windows, bins and drains can help. Bins should be emptied regularly and never used for liquid waste, which makes food rot faster and attracts more flies.
Odder remedies and a myth to skip
Flies also detest vodka, although spraying it is not advised unless a home smelling like a student bar the morning after is acceptable. They are also averse to cucumber, and chopped or sliced pieces left on a windowsill may help keep them away.
Food waste recycling tubs that attract flies can instead be stored in a carrier bag in the freezer until bin collection day. A trap can also be made by pouring sweet apple cider vinegar into a glass, covering it with clingfilm and poking a few holes in the lid, letting flies in but not out.
One method that does not work is filling a clear plastic bag with water, dropping in a few coins and hanging it by a window, on the theory that flies' fragmented vision will see multiple glittering images and fly off. In reality, flies simply ignore it.
