The annual influx of flying ants has arrived in the UK, with them set to swarm over the country as a result of hot and humid weather. 

The Met Office radar detected millions of bugs swarming over London last week.

Experts from pest control firm Rentokil, say "flying ant day" is the period when the insects begin to emerge from their nests to mate, coinciding with summer heat.

With temperatures expected to rise in the coming days, the firm says people will begin to see the swarming insects around the country.

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They have advised people to clean up after themselves straight away, keep things sealed and watch for ant nests in order to reduce the risk of an infestation. 

The Met Office tweeted on Sunday that "whilst there are a few rain showers, many of the echoes [on radar] are in fact insects".

Paul Blackhurst, Head of Technical Academy at Rentokil Pest Control said this is a common occurrence.

"Each summer thousands of flying ants emerge from their nests to swarm and mate," he said. 

Surrey Comet: Flying ants have been reported across south LondonFlying ants have been reported across south London

"Flying ants often come out in huge numbers as a survival tactic designed to overwhelm potential predators such as swifts and gulls.

"Often referred to as flying ant day, such events often occur in different areas of the country at different points across the summer months with flying ants emerging when weather conditions are favourable."

Why is Flying Ant Day a thing?

Flying Ant Day is scientifically referred to as nuptial flight, the phenomena where virgin queens mate with males before starting new colonies.

For humans this basically means a large quantity of ants whizzing around. 

The natural event has been described as "early Christmas" for seagulls, who enjoy feasting on the insects.

Surrey Comet: The Met Office posted this picture of the flying insects earlier todayThe Met Office posted this picture of the flying insects earlier today

While it has been dubbed 'Flying Ant Day', a project by the Royal Society of Biology found that the widely held idea is actually a misconception.

They found rather than a single day, it is more of a season. 

Swaming is triggered by the weather and tends to happen in July or August.

The study discovered that ants only flew on days when it was warm, not windy and conditions had improved compared to the previous day.

The interesting life of a flying ant 

Before the swarming or the nuptial flights, ants live in a colony in a nest and each have a specific job role. 

The queen lays the eggs while female workers look after the queen, eggs and larvae. They gather food, make their nest bigger and generally ensure the colony runs to plan. 

Most of the eggs hatch into worker ants but when the colony is completed, the queen begins to produce virgin queens and males. 

When the winged males and virgin queens emerge from the nest, they scatter to maximise the chance of mating between different colonies. 

Once ants have mated, the role of the males is over.

The mated queens quickly chew off their own wings and begin looking for a suitable site in which to nest and set up a new colony.

This is why you often see large ants walking around after a 'flying ant day' and may even see discarded wings scattered over pavements.

It usually happens at the end of July.

Why do ants sprout wings?

A new queen ant needs to leave the colony where she is born to found a new one. She also needs to mate. So, she leaves her nest with a number of flying male worker ants.

According to the Royal Society of Biology, the large numbers of flying ants which appear in a short space of time increase the chance of reproduction, because there is a very high chance a queen will encounter a male from another nest.

Then, to check he's worthy. she flies away from him, performing acrobatics to test his abilities to catch her.

When he does they mate in mid-air. This kills the male ant.

The Queen then lands to find somewhere to start a new colony. She loses her wings after just one day.