They are among the last things you'd want to see on a plane - or anywhere, for that matter.

So when a pair of creepy and aggressive stowaways revealed themselves on an Air Transat flight from the Dominican Republic to Canada, total mayhem was unleashed.

Passengers screamed and jumped onto their seats when the two tarantulas were spotted scurrying around the cabin shortly after dinner service on the April 18 flight.

"The spider crawled up my leg - I was in a skirt," passenger Catherine Moreau told Radio Canada.


"My husband managed to trap it in a plastic container, but its legs were sticking out.

"My daughter was screaming, she was in a state of shock."

Ms Moreau said it "took a long time from when we screamed to get a bag to put it in".

While the tarantula that crawled up Ms Moreau's leg was captured, its companion continued to roam the plane before it was eventually apprehended by a federal agent once the plane arrived at Montreal's Trudeau Airport.

Ms Moreau is now demanding a refund over her creepy encounter.

Julie Roberts, vice-president of Air Transat's flight attendant union, defended flight attendants on the plane, saying they "did what they could to calm people down".

"They gave first aid to the person who said that a spider climbed [up her] legs," she said, adding that hosties urged passengers to put on their shoes and cover their ankles.

Étienne Normandin, an entomologist at the University of Montreal, told Radio Canada the tarantulas were "aggressive, but the venom is not strong".

He said they were likely to be the species Phormictopus cancerides, which is "is very common in the Dominican Republic and Haiti, and easy to catch".

Mr Normandin suggested the tarantulas were hidden in a passenger's luggage so they could be sold on the spider black market.

"The market for live tarantulas is very lucrative," he said.

Air Transat acknowledged passengers were surprised by the cabin's spider invasion but "reacted calmly."

"Our cabin crew are trained to ensure the safety of our passengers at all times," spokeswoman Debbie Cabana told Radio Canada.

"In the case at hand, which is an unusual and isolated event, our staff reacted promptly and efficiently."

The airline is now reviewing procedures so they can better manage any future eight-legged stowaway situations in the future.