Once a year comes a day that many of us dread, when the skies fill with millions of insects, and picnics, pub gardens, and barbecues are suddenly under siege. It's called Flying Ant Day, and this summer could see the biggest swarms in years.

Pestcontrol experts are warning that this year's nuptial flight, when winged ants take to the air in huge numbers to mate, could be one of the most prolific on record. Rentokil Pest Control said the UK's recent mix of wet and hot weather, combined with high humidity, is creating ideal conditions for swarming.

Rentokil Pest Control told WalesOnline: "In past years, radar systems have even mistaken these dense clouds of ants for rain."

Paul Blackhurst, Technical Academy Head at Rentokil, added: "Experts warn that this year could see larger-than-usual swarms of flying ants, as we approach Flying Ant Day, also known as the nuptial flight, and sometimes nicknamed 'flant day'.

"This natural event, when vast numbers of winged ants, known as alates, take to the skies at once in search of mates from other colonies, could be one of the most prolific for years."

He explained: "The alternating wet and warm weather we have been experiencing recently is creating the perfect conditions for larger-than-usual swarms, as humidity is important in keeping the ants' wings and bodies moist during flight and 'mating on the wing'."

Despite the name, Flying Ant Day doesn't happen on a single date.

"These swarming events can occur at different times across the country, depending on the weather, and in particular, temperature, humidity and wind," Blackhurst said.

"While you might see a few flying ants on most warm summer days, ideal weather conditions can trigger the appearance of tens of millions of them taking to the skies in massive swarms over several weeks across Britain," he added.

"Though it may seem like a summertime nuisance, this swarming strategy is believed to help more ants survive by overwhelming their predators including swifts and gulls."

After mating mid-air, the males die while fertilised female queens shed their wings, burrow underground, and start new colonies.

While flying ants can be annoying, they also play an important role in nature, aerating soil, recycling nutrients and feeding birds.

To keep them out of your home, Rentokil recommends sealing entry points, cleaning up crumbs and spillages, using airtight containers, and installing fly screens to keep them outside.

The Express also revealed the six top tips on how to get rid of flying ants.