p-Menthane-3,8-diol is a naturally occurring compound that exerts a repellent effect on insects such as mosquitos and fleas. It is a colourless solid that is extracted from Eucalyptus plants or synthesised commercially. It comes in the form a racemic mixture of cis- and trans- isomers, with the cis isomer being more active than the trans isomer as an insect repellent.