High temperatures may make natural mosquito repellents less effective
In the journals
- Reviewed by Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
You may want to avoid mosquito repellents with certain natural ingredients when the temperatures reach the 90s, according to research published in the April 2025 issue of Pesticide Biochemistry and Physiology.
One way insect repellents work is by using chemicals that activate a pain receptor in mosquitoes called TRPA1, also known as the "wasabi receptor." In the study, researchers tested how the natural repellents citronella and catnip oil affected mosquitoes' wasabi receptors at a moderate temperature (around 73° F) and high temperatures (90° and above). They found the wasabi receptors were less active at higher temperatures, so the products were less effective at driving away the mosquitoes.
The team also tested the synthetic mosquito repellent DEET in normal and higher temperatures and found it still repelled mosquitoes at higher temperatures. DEET doesn't work on wasabi receptors. Instead, it offers protection from mosquitoes by masking the smell of humans, a process not affected by high heat. According to the researchers, the findings suggest that on very hot days, people may want to use a conventional synthetic repellent.
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About the Author
Matthew Solan, Executive Editor, Harvard Men's Health Watch
About the Reviewer
Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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