For those who know me.. I hate bugs! The thought of relaxing outside with a bunch of mosquitoes flying at you is repulsive. So having an effective bug spray is a must. There are many varieties in the drug store with one common ingredient - DEET.
What is DEET and is it effective?
This is hotly debated topic. DEET is a chemical compound - N,N-Diethyl-meta-toluamide, or diethyltoluamide. Scientists can’t all agree on the mechanism of how DEET works but one of the ways that has been shown in many studies is that it sends out a signal to bugs (and mosquitoes) that messes up how their receptors perceive odors in the air. (1). “A new study (in 2012) in fruit flies by Howard Hughes Medical Institute investigator Leslie Vosshall, a neurobiologist at The Rockefeller University in New York, suggests that DEET confuses insects by jamming their odor receptors”. (1)
Mosquitos target humans by smell. They have antennae with olfactory nerves at the end which bind to proteins in the air that would either attract or deter them away from a particular object (ie. a human). The chemical composition of humans vary widely. Research has shown that mosquitoes are attracted to the carbon dioxide we exhale (so don’t breathe folks), lactic acid, our sweat, and things like your blood type (8), whether you are pregnant or not, and what you are eating and drinking all have a factor in the chemical composition we give off to these pesky insects.
So why is it bad? Why do I need to make my own bug repellant?
There has been documented cases of harmful side effects when someone has been in contact with DEET such as chest pain, wheezing, rashes, muscle cramps, dizziness and disorientation (2). It is also has been shown to cause diffuse neuronal cell death in the brain (3) and decrease activity in the brain along with neuromuscular function (4).
How to DIY a mosquito blend
So I had made a blend a while ago which comprised of witch hazel, citronella, and tea tree oils and used it a few times. Unfortunately I did not see any difference - still got eaten alive!
Here’s why (or at least why I think so):
According to some of the research I’ve read, when we use commercial repellents, the spray with DEET coats your skin and stays in your system longer than these essential oils. Remember essential oils get quickly metabolized in our bodies compared to these synthetic compounds (read my Essential Oil Series - Part 2). So I may not have reapplied as often as I should have. If we can mask whatever scent mosquitoes are attracted to - we shouldn’t get bitten.
New & Improved DIY Blend
Carrier oils shown to be effective are Neem Oil, Soybean Oil, Coconut oil. This is likely due to the fact that they reduce short range attractive cues, reduce evaporation and absorption of the repellent, and contain fatty acids which tends to repel mosquitoes. (5). This is why witch hazel may not have been the best choice to use.
A product called ‘Bite Blocker’ uses 2% Soybean Oil as an alternative to DEET which “provides protection for 3.5 h against mosquitoes (and up to 8 h against black flies). There are no age restrictions or limitations on frequency of use”. However, they may not protect from tick bites and those sensitive to plant oils may develop dermatitis or eye irritation. (6).
Final product should include a carrier oil and a mixture of essential oils.
Carrier oil: Either Neem oil, Soybean, or Coconut oil.
Essential oil: One or a mixture of 15 drops of Citronella, clove, Lemon Eucalyptus, Patchouli, Peppermint, Thyme.
Mix in a glass bottle such as 2 oz cream pump/spray bottle.
Apply frequently (every hour or so) directly on the skin. (7). Different compositions of these oils may work differently for each person because we are all comprised of a different chemical make-up. So if it doesn't work don't throw it away! Let someone else in your family try it out because it could work for them! Have them handy because different species of mosquitoes may also prefer different scents.
1. Howard Hughes Medical Institute. (2011). How does DEET work? Study says it confuses insects (Update). Retrieved from https://phys.org/news/2011-09-deet-insects.html
2. U.S. Department of Health and Human Resources. (2017). TOXICOLOGICAL PROFILE FOR DEET (N,N-DIETHYL-META-TOLUAMIDE). Retrieved from https://www.atsdr.cdc.gov/toxprofiles/tp185.pdf
3. Abdel-Rahman A, Shetty AK, Abou-Donia MB. (2001). Subchronic dermal application of N,N-diethyl m-toluamide (DEET) and permethrin to adult rats, alone or in combination, causes diffuse neuronal cell death and cytoskeletal abnormalities in the cerebral cortex and the hippocampus, and Purkinje neuron loss in the cerebellum. Experimental Neurology, 172(1):153-71. Doi: 10.1006/exnr.2001.7807.
4. Mohammed B. Abou-Donia, Larry B. Goldstein, Katherine H. Jones, Ali A. Abdel-Rahman, Tirupapuliyur V. Damodaran, Anjelika M. Dechkovskaia, Sarah L. Bullman, Belal E. Amir, Wasiuddin A. Khan; Locomotor and Sensorimotor Performance Deficit in Rats following Exposure to Pyridostigmine Bromide, DEET, and Permethrin, Alone and in Combination, Toxicological Sciences, Volume 60, Issue 2, 1 April 2001, Pages 305–314, https://doi.org/10.1093/toxsci/60.2.305
5. Maia, M. F., & Moore, S. J. (2011). Plant-based insect repellents: a review of their efficacy, development and testing. Malaria Journal, 10(Suppl 1), S11. http://doi.org/10.1186/1475-2875-10-S1-S11
6. Canadian Paediatric Society. (2014). Preventing mosquito and tick bites: A Canadian update. Retrieved from https://www.cps.ca/en/documents/position/preventing-mosquito-and-tick-bites
7. Z. Eric. (2014). Essential Oil Mosquito Repellent Recipe. Retrieved from: https://drericz.com/essential-oil-mosquito-repellent/
8. Landing Preference of Aedes albopictus (Diptera: Culicidae) on Human Skin Among ABO Blood Groups, Secretors or Nonsecretors, and ABH Antigens
Yoshikazu Shirai, Hisashi Funada, Hisao Takizawa, Taisuke Seki, Masaaki Morohashi, and Kiyoshi KamimuraJournal of Medical Entomology 2004 41 (4), 796-799.