Huge swarms of flying ants that hit England’s south coast were mistaken by weather satellites in space for clouds of rain.

The Met Office’s radar captured what it described as “insect clutter” over the counties of Hampshire, West Sussex and Dorset on Wednesday morning. They were also spotted in East Sussex and Kent.

“It’s all about mating,” insect expert Prof Adam Hart of the University of Gloucestershire said. “The ant colonies in the ground are busy rearing the potential new queens and males. When the weather conditions are right, they go into the air.”

The weather in the south of England has triggered what is known as the “nuptial flight” phase of the ant’s reproductive cycle – commonly referred to as a “flying ant day”.

But Prof Hart argues that the term is misleading as the mating ritual can last for several weeks throughout July and August, depending on the weather conditions in different parts of the country, ultimately involving billions of ants.

The ants typically take to the skies when rainfall is followed by hot, humid weather. The queen emits pheromones as she takes flight, encouraging the males to pursue her. But only the strongest are able to mate with her.

As the queen flees their advances, birds swoop in and prey upon them. The chase is intended to ensure that the queen’s offspring are as fit as they can be.

“The ones that don’t get eaten by birds fall to the ground and lose their wings,” Prof Hart said. “The queen then digs a little hole and tries to start a new colony … It is one of nature’s spectacles. It is fantastic to see the exuberance of nature.”

A Met Office spokesperson said the ants showed up on their image as showers of rain because “the radar thinks the beams are hitting raindrops, not ants”.

Simon King (@SimonOKing) Flying ants!!!



Swarms of them flying into the sky in S Eng are being picked up as rain on the radar image this morning...!#flyingantday #flyingants 🐜🐜🐜🐜#yuk pic.twitter.com/QGOcikqJFq

Flying ants are harmless to humans, but it has been reported that they can have a strange effect on seagulls, who can appear drunk after eating a few. “Some think it’s to do with the formic acid in the ants,” said Hart. “But the jury is still out on that one.”

He suspects the satellite sighting of the swarms is more likely attributable to increasingly sophisticated technology than to an increase in the ant population. “If it is increasing, I think it is a potentially a good thing,” he said. “But I would be cautious to interpret that.”