Natural insect repellents have become popular in recent years. None of them, however, have been found to be as effective as high concentrations of DEET. Here is some information about some of the better known natural insect repellents.
The active compound in the lemon eucalyptus plant, extracted from the leaves and twigs, is thought to be p-menthane-3,8-diol. It can also be chemically synthesized. Lemon eucalyptus oil is thought to repel mosquitoes, biting flies and gnats. It is found in a spray or lotion.
According to Consumer Reports, a lemon eucalyptus product called Repel received a higher overall score than the 7% DEET insect repellents tested and scored almost as high as two of the 20% DEET insect repellents. Volunteers in the tests, however, criticized the odor. A 2002 study in the New England Journal of Medicine found that Repel offered 120.1 minutes of protection time against mosquitos.
In the Consumer Reports evaluation, none of the other plant-based insect repellents performed nearly as well.
Some of the more common natural alternatives include citronella or the oil of geranium, lemon grass, cedar or soy. One analysis of various plant essential oils found catnip oil to be promising for mosquitoes.
Consumer Reports. Insect Repellents. Quick Ratings. June, 2006.
Fradin MF, Day JF. Comparative efficacy of insect repellents against mosquito bites. New England Journal of Medicine. (2002) 4,347(1): 13-8.
Zhu J, Zeng X, Yanma , Liu T, Qian K, Han Y, Xue S, Tucker B, Schultz G, Coats J, Rowley W, Zhang A. Adult repellency and larvicidal activity of five plant essential oils against mosquitoes. J Am Mosq Control Assoc. 2006 Sep;22(3):515-22.