Flying Ant Day UK: When It Happens, Why Ants Fly and What Happens Next

One minute your patio looks normal. The next it’s covered in flying ants, pouring out of the paving, climbing over each other and lifting off into the air.

This is Flying Ant Day, though the name is a bit misleading. There isn’t one day when every ant in Britain takes off. There’s a flying-ant season, and each colony flies when it’s ready and the local weather allows. For the familiar black garden ant, Lasius niger, that mostly means July and August. Other British species can fly much earlier or later.

The flying ants aren’t a separate species either. They’re the reproductive males and young queens produced by established colonies, leaving to mate and, for the lucky few queens, to found colonies of their own. If your garden suddenly seems full of them, nothing is usually wrong. You’re watching one of the most important events in a colony’s life.

To follow what happens after a queen starts laying eggs, see our Ant Life Cycle guide, from eggs and larvae to workers and mature colonies.

When is Flying Ant Day in the UK?

For black garden ants, July is the main month, with flights often continuing through August. Don’t circle a date on the calendar, though.

Between 2012 and 2014, the Royal Society of Biology and researchers at the University of Gloucestershire ran a national Flying Ant Survey. The public reported when and where they saw winged ants, giving the team more than 13,000 usable sightings. The results didn’t support a single national day:

  • About 65% of sightings fell in July and about 33% in August, with a small tail in June and September.
  • The busiest days changed from year to year. The biggest single-day peaks were 24 July in 2012, 1 August in 2013 and 17 July in 2014.
  • Flying ants were reported somewhere in the UK on 68 of the 97 survey days in 2012 and 2013, and on 93 of 97 in 2014.
  • Nearby areas often peaked on different days. The researchers found no significant geographical clustering of sightings at national, regional or London scales.

What people experience as Flying Ant Day is a series of local events. One town can be swarming on a Tuesday while somewhere a few miles away peaks a week later.

Some small geographical patterns did show up. Flights tended to come a little later further north and west, and colonies in urban areas or in warm spots such as under paving, brick walls or compost heaps flew about three days earlier on average. These effects were real but weak, and local weather mattered far more.

There are two limits to bear in mind. The survey only ran from 1 June to 4 September, so earlier and later flights couldn’t be recorded, and “June to September” is partly a product of that window. It also excluded Northern Ireland. The figures describe three summers, not a rule for every future year.

You can read more in the original paper and in the Natural History Museum’s explanation of flying-ant swarms.

When is Flying Ant Day 2027?

Nobody can say yet, and there’s no reliable way to predict it months ahead. If you want to see black garden ants fly, watch in July and August. A warm, calm spell may set off several nearby colonies at once, but even neighbouring gardens can have their main flights on different days. Any site quoting an exact date well in advance is guessing.

What weather brings flying ants out?

You’ve probably heard that it’s hot, humid or just after rain. Parts of that are true, but the research is more specific.

The survey found two clear relationships. Winged ants were reported more often on warmer days and less often on windy ones. Sightings were also more likely when conditions had improved on the previous day: rising temperature, easing wind, or both. That fits what the ants are trying to do. They’re small insects leaving the nest to fly into unfamiliar territory, and warm, still air makes that easier and probably safer. The authors suggest the ants can judge, at least in a limited way, whether the weather is getting better or worse.

Is there a temperature that triggers it?

Not a fixed one. In the survey, sightings were reported at daily mean temperatures above 13 °C and daily mean wind speeds below about 14 mph (6.3 m/s). Those numbers are averages from the nearest weather station, not measurements taken in a garden at take-off, and they describe where the sightings fell, not the point at which an ant physically can’t fly. Every day with a mean temperature above 25 °C had sightings somewhere, but that shows very warm days were reliably productive, not that ants need 25 °C.

In practice, a warm afternoon with little wind, especially after the weather has been improving, is the best bet during flying-ant season.

What about rain and humidity?

Recent rain could plausibly help: damp soil may make it easier for a new queen to dig her first chamber. The Natural History Museum describes the link between rain and flying ant days as anecdotal. The national survey couldn’t test it, because it only had monthly rainfall totals, so it neither supports nor rules out rain as a trigger. An older Dutch study (Boomsma & Leusink, 1981) found that humidity and sunlight were associated with flights of Lasius niger, L. flavus and Myrmica rubra. Different species clearly like different conditions.

So Flying Ant Day isn’t something that automatically follows a summer shower. The best general guide is warm, fairly calm weather when a colony already has reproductives ready to go.

Why do ants suddenly have wings?

They haven’t grown wings because the weather changed. A mature colony produces different kinds of ant. Most are workers, which are wingless females that forage, maintain the nest and look after the young. An established colony can also produce a generation of reproductives: males and young females that can become queens. Winged reproductives are called alates.

Alates are expensive to make, which is why a tiny, newly founded colony doesn’t normally produce them. By the time you see them gathering at a nest entrance, the colony has been preparing for weeks or months. What decides whether a female larva becomes a queen or a worker isn’t simply extra food. Nutrition, hormones, genetics and how the adults care for the larvae all play a part, and the details vary between species. Suitable weather doesn’t create the reproductives. It gives the colony the chance to release them.

Are all flying ants queens?

No. Both males and future queens have wings. Winged queens and males have four wings in two pairs. The smaller hind wings hook onto the front pair in flight, so they’re easy to miss.

  • Queens are larger and heavier than males of the same species. Their middle body section (the mesosoma, which ant keepers often call the thorax or alitrunk) is deep and bulky because it houses the flight muscles.
  • Males are usually slimmer, with a relatively small head and large eyes.

The differences between queens, males and workers are easier to understand when you compare the middle sections of their bodies. My Queen Ant Identification Guide explains what to look for, while Ant Anatomy Explained shows where the main body parts are. For real specimen photographs, the BWARS species gallery and AntWeb are useful references.

Are they all black garden ants?

Black garden ants account for a large share of the swarms people notice. In the survey, 386 of the 436 ants returned for identification in 2013 (88.5%) were Lasius niger. Most of the rest were the yellow meadow ant, Lasius flavus, with a scattering of other species. Britain has plenty of other ants with their own flight seasons, and some are hard to identify even from a good photograph. Our British Ant Identification Guide covers the main groups and their lookalikes.

What happens during a mating flight?

When conditions suit, the reproductives leave the nest and disperse. This is the mating flight, or nuptial flight. Males and young queens from many nests meet, which helps queens spread into new areas and reduces the chance of mating with close relatives.

In species such as Lasius niger, males gather in large numbers and queens join them. We usually picture ants mating in mid-air, but that isn’t universal. Some species are reported to mate on the ground or on vegetation.

Does a queen mate with lots of males?

It depends on the species. A genetic study of 535 Lasius niger queens from seven north-western European populations found that most had mated with a single male. Some mated twice and one mated three times. The pattern varied between populations, so “usually once” is a fair summary of this study rather than a rule for every queen. You can read the details in Boomsma & van der Have's research on Lasius niger mating.

How can a queen lay fertilised eggs for years after one flight?

She doesn’t need to mate again. After mating, she stores sperm in a specialised organ called the spermatheca and uses it to fertilise eggs over a long period, potentially much of her life. Scientists are still working out how stored sperm stays viable for so long, and recent work on Lasius niger has looked at changes to the proteins surrounding it. It’s remarkable that all of this starts with a short event on a summer afternoon.

What happens to the queen afterwards?

Once she has dispersed, a queen needs somewhere to begin her new life. You’ll often see them walking across pavements and lawns, usually with their wings already gone.

Does losing her wings mean she’s mated?

Not reliably. The wings break off at special attachment points, leaving small wing scars. A wingless queen may well have mated, but virgin queens of some species can shed their wings without mating, and a winged queen isn’t automatically unmated. Wing loss is a useful clue to a newly dispersed queen, not a fertility test.

Even eggs aren’t proof. In the usual ant system, unfertilised eggs develop into males, so for normally reproducing species like Lasius niger, the arrival of female workers is much stronger evidence that she mated.

How does a queen start a colony?

Take the black garden ant as an example. A mated queen finds a patch of soil, digs a small chamber, seals herself in and starts laying eggs. She doesn’t normally leave to forage while raising her first brood. She lives on reserves stored in her own body, which is called claustral founding. The eggs hatch into larvae, then pupae, and eventually the first workers emerge. They take over foraging and the colony can start to grow.

Many queens never get that far. Some are eaten, and others fail because of poor nest sites, disease or problems during founding. There isn’t a reliable survival rate for wild queens, and laboratory success rates shouldn’t be treated as a prediction for a British garden.

Not every queen can found a colony alone

This matters if you’re thinking of keeping ants. A queen of Lasius umbratus is a temporary social parasite. According to BWARS, she founds her colony by invading a nest of another Lasius species, usually Lasius niger, L. platythorax or L. brunneus, and relies on the host’s workers to raise her first brood. Treating her like a black garden ant would be a serious mistake. Identify the species before deciding how to care for it, and never add random workers to a queen or put her into an established colony.

And the males?

Their story is shorter. Males don’t build nests or found colonies, and they generally die soon after the mating period. You’ll sometimes read that all males die within 24 hours of mating, but that’s too precise, because lifespan varies between species and circumstances. For the males the flight is close to the end of their lives. For a successfully mated queen it may be the start of a colony that lasts for years.

Why do so many ants fly at once?

Picture hundreds of mature colonies scattered through a town, all developing through the same summer under similar weather. When a warm, calm afternoon arrives, several may be ready at the same moment. Shared weather is the best-supported explanation for why local colonies fly together.

There may be other advantages too. Having lots of reproductives in the air creates more opportunities to meet mates from other colonies and helps new queens disperse away from their parent nests.

Large swarms might also reduce predation risk in two related ways. Predator satiation is when predators have more prey available than they can eat. The dilution effect is when an individual ant's chance of being caught may be lower among thousands of others. Both ideas are plausible, but neither has been established as the main reason British black garden ants fly in large numbers.

Why do gulls eat flying ants?

They do. A swarm is a sudden, short-lived supply of insects, and you can often see gulls and other birds concentrating on it. The popular story that the formic acid in the ants makes gulls drunk is repeated in many news articles, but I’m not aware of controlled evidence that it happens. The birds may simply be excited by the abundance of food. It’s a fun story, but it shouldn’t be presented as fact.

Do flying ants bite or sting?

For a typical black garden ant swarm, flying ants are not a serious danger. They aren’t emerging to attack anyone. Black garden ants can nip with their jaws if handled or trapped, but they don’t have a functional sting. Like other formicine ants, they defend themselves chiefly by spraying formic acid.

“Flying ant” describes a life stage, not a species, so the answer depends on which ant you have. Red ants of the genus Myrmica, for example, can sting and cause local irritation. The Royal Horticultural Society’s guidance on ants makes the same distinction and encourages people to tolerate garden ants where possible. If you’re watching a swarm, give the ants space and avoid handling unfamiliar species.

What should you do if flying ants appear in your garden?

Usually nothing. A mating flight is a normal part of a healthy colony’s year, and the activity will settle on its own. There’s no good reason to destroy a nest or spray insecticide just because you’ve seen a swarm. Ants move soil, clear up dead insects, hunt small invertebrates and feed other wildlife. They can be a nuisance when nesting in lawns or plant pots, but their presence doesn’t mean something needs treating.

If you can, watch. You might see workers crowding around an entrance, winged ants climbing over one another before take-off, and later the larger queens walking away across the paving.

What if they’re coming into the house?

First work out whether they’re flying in from outside or emerging from somewhere inside. A few winged ants near an open window during a summer swarm have probably just wandered in. Opening a window or door to let them out is usually enough, and you can keep food covered until the activity passes.

Finding large numbers coming from the same crack in a floor, or a gap near a skirting board, is different. That may mean a nest in or right beside the building. If it continues, identify the ant and find where it’s coming from before deciding on any treatment, because species differ in their nesting habits and not every indoor ant problem involves black garden ants. I wouldn’t recommend pouring boiling water into gaps, using random household chemicals or destroying nearby outdoor nests simply because flying ants have appeared.

Do all British ants fly at the same time?

No. The July and August black garden ant flights are one part of a much longer reproductive season, and the table below shows a rough guide to some of the better-documented species.

Ant species Typical British mating-flight period
Southern wood ant, Formica rufa Spring to early summer
Black garden ant, Lasius niger Mainly July to August
Yellow meadow ant, Lasius flavus Roughly late July to August
Common red ant, Myrmica rubra Roughly August to September
Lasius umbratus Mid-August to late September

These are typical periods, not exact dates or guarantees. Weather, region and habitat all move them. The Bees, Wasps and Ants Recording Society (BWARS) is the best place to explore individual species’ habitats, distribution and flight times. For some British species the timing is poorly documented, so a calendar borrowed from elsewhere in Europe may not fit.

Found a queen after Flying Ant Day?

You may find a large queen walking along a pavement shortly after a swarm, often with her wings already gone. Before you collect her, remember that British queens don’t all have the same needs:

  • A black garden ant queen can normally found a colony independently on reserves stored in her body.
  • Other species need to forage while founding.
  • Some, like Lasius umbratus, need a host colony.

If you can’t identify her, you can’t know what she needs. Start with the British Ant Identification Guide, then read what to do after catching a queen ant. If you’ve confirmed an independently founding species and plan to keep her, the next step is learning how to set up a queen-ant test tube properly. It’s also worth reading about whether queen ants need food during founding, as this varies by species. You don’t have to collect a queen just because you’ve found one. Watching her disappear into the soil is as much a part of Flying Ant Day as keeping a colony.

Got a knack for ant photography?

I’m gradually building a collection of photographs to help people learn about British ants. If you’ve taken good shots of flying ants, queens, mating flights or British species, I’d love to hear from you.

Email antastictom@gmail.com with your photographs, the species if you know it, and roughly where they were taken. Please only send photographs you’ve taken yourself or have permission to share. Tell me how you’d like to be credited, and I’ll confirm permission before using anything on the website.

Common questions

How long does Flying Ant Day last?

A noticeable burst from one local nest may be over within hours. Other colonies may fly later the same day or on other days, and across Britain the season lasts for weeks to months.

Can one colony produce flying ants more than once?

Yes, it can happen. Hart and colleagues note that nests may produce several batches of reproductives in a good season, with a main flight followed by smaller ones. The national survey didn’t track individual colonies, so there’s no reliable figure for how often this happens.

Will flying ants come earlier because of climate change?

Temperature clearly affects flying-ant activity and Britain is warming, but the national survey covered only three summers. That isn’t enough to show a long-term shift in black garden ant flight dates. It’s a reasonable question for future research, not a settled answer.

Can weather radar detect flying ants?

Radar can sometimes pick up large numbers of insects in the air, and dense swarms have even shown up on British weather radar looking like rain. But identifying a species from radar is very difficult, so it can’t yet predict when and where a black garden ant flight will happen.

The next time it happens

For most of the year, the reproductive side of an ant colony stays hidden in the nest. You see workers carrying food across the garden and have no idea what’s developing underground. Then one summer afternoon a mature colony releases the males and young queens it has spent months producing. Some will find mates, many won’t survive, and a few queens may found colonies somewhere nearby: under a paving slab, in a patch of soil, at the edge of the lawn.

So next time hundreds of flying ants pour out of a crack in the patio, have a look before reaching for the spray.

Sources and further reading