It's not every day that you come across a swarm of hundreds or thousands of bugs, but you might be surprised to know what causes them.

On the weekend, a Saskatchewan woman shot a video showing swarms of insects near Old Wives Lake. It looks like mini tornadoes, but is actually swarms of mayflies.

Entomologist Sean Prager says mayflies swarm during mating.

Sean Prager, who is an entomology expert and assistant professor at the University of Saskatchewan, said there are a variety of reasons why so many mayflies might be around, including the weather conditions this year, or in the past few years when the bugs' eggs were laid.

The more than 100 species of mayflies in Saskatchewan are aquatic for most of their lifetime. Their eggs are typically laid on water.

Eventually, they emerge and mate, which is exactly what's going on when you come across a "swarm."

Busy bees make a move

On Sunday, a Westjet flight was delayed at the Saskatoon John G. Diefenbaker International Airport when thousands of bees descended on the vehicle used to push the aircraft back from the gate.

According to Prager, bees swarm when their hives get too crowded.

He said a new queen will leave with a bunch of workers to establish a new colony somewhere else. Sometimes along the way they need to stop while they assess where they want to set up their new nest.

Bees are really just taking a pit stop when they swarm, according to Prager. (Maja Dumat, flickr cc)

"It's most likely that the airport just happened to be between where they were and where they were going and the little truck thing that they landed on was just a random item that they decided would be a good place to stop," Prager said.

On the way to their new home, Prager said the queen will pick a place to rest while scouts go out to look for a place to relocate.

Prager said bees prefer blues and yellows and can also be drawn to a place due to smell.

These swarms, caused by bees on the move, always happen in the summer after the hives get fairly big.

According to Prager, a local beekeeper used a smoker to sedate the bees. He then collected them to move them out of the way.

In a bit of good news, Prager said the province is at the tail end of the season for most bugs, besides mosquitoes and blackflies.