Study summary
Repellency of essential oils to mosquitoes (Diptera: Culicidae)
Barnard DR
Read the original paper- Study type
- Lab
- Year
- 1999
- Species tested
- Aedes aegypti
- Published in
- Journal of Medical Entomology 36(5):625-629
- Evidence strength
- Well-supported evidence
How it was tested
Laboratory cloth-patch and skin assays of essential oils against laboratory-reared mosquitoes.
Summary
A controlled study measuring how long five essential oils, alone and in blends, keep mosquitoes from biting treated skin across a wide range of concentrations. It sets a clear hierarchy and shows these oils do nothing at low doses.
Key findings
Thyme and clove were the best, giving roughly 1.5 to 3.5 hours of complete protection depending on concentration, while cedarwood failed entirely and peppermint worked only at high strength. No oil prevented bites at 5 or 10%. Certain 50/50 blends, clove with geranium and clove with thyme, protected against a malaria mosquito for 1.25 to 2.5 hours. The catch is that the effective concentrations, 25% and up, tended to irritate skin and smell strong.
Limitations
The concentrations that worked also caused irritation and strong odor, protection was reported as concentration ranges rather than single values, and only two mosquito species were tested.