Oil of lemon eucalyptus (OLE) is an effective mosquito repellent due to its active agent, PMD (p-menthane-3,8-diol), which is a natural compound extracted from the leaves of the lemon eucalyptus tree (Eucalyptus citriodora). PMD has been found to be as effective as synthetic insect repellents like DEET in repelling mosquitoes.

When applied to the skin, PMD works by masking the human scent and interfering with the mosquito's ability to locate its target. Mosquitoes are attracted to humans by the carbon dioxide we exhale, as well as other chemicals and compounds found in our sweat and body odor. By disrupting the mosquito's ability to detect these chemical signals, PMD makes it harder for them to find and bite humans.