They first arrived as pets the 1960s before escaping into the wild and colonising the wildlife havens of southern Florida.

Since then, green iguanas have taken over, wreaking havoc in the form of stripped vegetation, power outages and contaminated swimming pools.

This summer is looking like the worst year anyone can remember, with packs of the distinctive green lizards taking over pavements and gardens.

Richard Engeman, a biologist for the National Wildlife Research Centre, told The Sun Sentinel newspaper: “There’s no real way to come up with a valid estimate of the number of green iguanas in Florida. But the number would be gigantic.

“You could put any number of zeros behind a number, and I would believe it.”