TINY TOWNSHIP, ONT. -- Millions of Gypsy moth caterpillars are crawling and eating their way across cottage country.

The moth is more than five-centimetres long and native of Europe and Asia. They arrived in North America in the 1860s.

The invasive species eat a wide variety of trees but prefer oak.

A cyclical plague returns every five to seven years, but this is the worst infestation in cottage country in three decades.

"We've never seen it this bad, and I've been here for over 40 years," said Tiny Township cottager Lori Petrucci.

Brett Dixon is an arborist and professional forester with the County of Simcoe, where the insect larva have been chewing their way through swaths of forest.

Dixon said most trees would survive the attack and that nature has a way to controlling their numbers.

"There is a virus and also a fungus that usually brings that population back down," Dixon explained. "Oftentimes, especially the oak trees, they will put out a second leaf."

He added that he's started seeing signs that the virus is taking its toll on the caterpillars.

Many of the caterpillars are starting to pupate and will soon emerge as white or grey moths.

Watering can help to reduce the stress on valuable trees.