Common caterpillars in southern Ontario are getting some unusual attention after health units in the region issued a special advisory.

You might not want to touch the hickory tussock moth caterpillar.

“The main reason the caterpillar has poisonous spines is for protection against anything that might eat it,” says Paul Pratt, City of Windsor naturalist.

If the spine of the hickory tussock moth caterpillar is rubbed or touched it could inject a small amount of venom into you.

According to the Middlesex-London Health Unit, that's a good thing, because touching one can cause a rash a burning sensation pain, swelling and even headaches and nausea.

“Usually the most severe reactions are from small children who have maybe put one in their mouth," says Pratt.

Children are learning about the insect at the Ojibway Nature Centre, where the creature is quite common.

Eventually the caterpillars turn into moths

“They'll be around for the next couple weeks and then they'll transform into their cocoons," says Pratt.

If you happen to encounter a hickory tussock moth caterpillar, you should wash your hands with soap and water, use ice if there's any swelling and seek medical attention if you experience an allergic reaction.

“For a lot of people the reaction is similar to if you've brushed up to stinging nettles," says Pratt.

While the creature has been around for a very long time, Pratt says it's good to remind people and offer a lesson in nature.