How Mosquito Repellents Work

How mosquitoes find us:

Before we can understand how mosquito repellants work, we need to understand how mosquitoes find us in the first place.  Unfortunately for us, mosquitoes have evolved 3 ways of seeking out a meal. Each of these methods, used in tandem, enables them to fly in for the bite.

  1. 33 – 99 feet: At this distance mosquitoes rely on their sense of smell, specifically the CO2 plumes we, or other animals, emit.  Experiments have shown that the female mosquito only pays attention to the next cue once the first is present and they are closer to the source.
  2. 15 – 33 feet: The mosquito has homed in on the scent and at this distance is now searching for visual clues to spot you.  They are seeking the source of the CO2, not for a shape or body. 
  3. 1 – 3 feet:  The mosquitoes now rely on thermal sensory input to locate heat and moisture sources.  This prevents them from wasting time on objects such as a rock or vegetation.  

Mosquito repellents are designed to block the mosquito’s sense of smell in stage one.  This is important as it means that someone standing next to you, without repellent, will be attracting mosquitoes.  Of course, once the insect is within 33 feet of you, it now will not distinguish between you and your un-protected friend, meaning you are equally as likely to be bitten as they are.  We often hear people tell us that mosquito repellents don’t work. This is not necessarily true and is more a factor of those around you, as well as how well the repellent has “stuck”.  For example, if you are out in the yard with your spouse, and they just happen to sweat a lot, the repellent may have run off them. Hence, they are the magnet bringing them in to bite you.

What repellents do:

So how do repellents work?  DEET was developed by the military over 50 years ago but it was only more recently that studies have been done to understand exactly what it does.  Mosquitoes smell with their antennae, which are covered in olfactory nerves. The nerves are essentially equipped with odor receptors, that bind to odor molecules and trigger neural activity.  Simply put, DEET binds to these receptors leaving the mosquito confused and unable to smell you. The DEET over-activates the receptors rendering their ability to smell useless. 

According to many studies, the only repellent that comes close to the ability of DEET is lemon eucalyptus oil with the caveat that natural products break down faster and thus must be applied more regularly.  It should not be applied in its pure form and is also not recommended for children under the age of 3. Do not confuse it with the essential oil of lemon eucalyptus either (easy to do). Lemon eucalyptus oil has a different mode of action, simply creating a powerful smell to override that of CO2.  

The market is saturated with alleged mosquito repellents.  Wearables have become popular, although scientific studies show they are not capable of repelling mosquitoes.  Many people prefer to stay away from DEET and make natural repellents. We wrote a blog about DIY repellants recently and you can check out more here. However, they have not been proven to be effective in the fight against mosquito bites.  Folks also like to burn citronella candles and burn tiki torches, but these again will only confuse and delay you being found. 

It’s not enough to wear repellent in your own yard.  The most effective way to avoid or reduce the bites in your own yard is to remove all stagnant water sources from it.  Remember, one small capful of water is enough for 300 eggs. The more water you remove the better you will be. Of course, calling us to manage that water and treat your yard is the best way we know to make your outside fun.  Then you can ditch the repellant and just enjoy.

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