When cats rub, roll against and chew catnip, it looks like they’re just doing it for a kitty high. But that type of play also releases compounds in the plant that protect the cats from mosquitoes, reports CNN.com.

Researchers discovered last year that the iridoids found in catnip and silver vine, another flowering plant, act as an insect repellent when released through rubbing or macerating. The same team has now found that the specific way in which cats lick and chew the plant makes the leaves release 10 times as much of the compound—making catnip all the more repellent to insects. The researchers also determined that it’s the smell of the plant that triggers the cats’ intense behavior. “Cats still exhibited licking and chewing even when they couldn’t contact the chemicals directly,” says lead author Masao Miyazaki, from Iwate University in Japan. The study said the findings might help researchers identify plant enzymes that could be used as insect repellents for humans.