Donald R. Lewis of Iowa State University's Department of Entomology reports that lemon thyme (Thymus X citriodorus) is approximately 62 percent as effective at repelling mosquitoes as DEET, a powerful chemical that is the active ingredient in many commercial mosquito repellents. This puts lemon thyme ahead of the citrosa plant, which is approximately 30 percent to 40 percent as effective as DEET.
How to Use
Unfortunately, surrounding yourself with pots of lemon thyme will not keep mosquitoes at bay, and neither will sprinkling it on your salads and eating it. In order to take advantage of lemon thyme's mosquito-repelling properties, you must crush the leaves and rub the resulting oils onto your skin.
Growing Lemon Thyme
If you grow your own lemon thyme, you'll always have some on hand for crushing and using as mosquito repellent. Lemon thyme grows well in beds or in containers and typically requires very little care. Plant it in full sun and in well-drained soil. Water it on a regular basis, but do not allow it to sit in soggy soil for long periods. Around midsummer, cut the plant back to about two inches and let the foliage grow. This gives it a better chance of surviving winter.
Crushing lemon thyme leaves and rubbing the oil on your skin causes skin reactions in some people. Before applying lemon thyme oil liberally, test your skin's tolerance on a small, inconspicuous spot on your body. There are many varieties of thyme. Make sure you purchase lemon thyme if your objective is repelling mosquitoes.