Avoid the bite


You may have noticed it’s been raining a bit as of late, so much so that we’ve received 50-75% more rain than average this spring. No doubt this fact hasn’t gone unnoticed by the mosquitoes as it means their preferred breeding grounds (stagnate pools of water) will now be readily available. Just think, right now there are millions upon millions of larvae hatching allover the GTA. Soon a bumper crop of the little devils will set out looking for a meal – An awful Bildungsroman of which you’ll be the butt of the joke.

Sure, it isn’t the end of days, but it won’t be a picnic in there, so you better know what you’re doing. As fellow riders who have spent quite a while in the forest we’re offering to help you make some reasonable choices when it comes to bite prevention.

As I see it, there are two main factors at play in dodging the majority of mosquitoes. The first one is which type of repellent you’re planning to use. I’ve collected a few handy study summaries to help you decide which chemical seems to work best. The first comes from a tiny study described as follows:

Dr. M.S. Fradin (Chapel Hill Dermatology, Chapel Hill, NC) and Dr. J.F. Day (Florida Medical Entomology Laboratory, University of Florida, Vero Beach, FL) tested the insect repellents on 5 men and 10 women volunteers. The volunteers put their arms into a test cage that contained 10 hungry female mosquitoes and the researchers recorded the time until the first bite. (2)

As you can see, the higher the concentration of DEET in a repellent the longer a subject could last without being bitten. Now keep in mind this experiment is done inside a lab, not the forest so the “Time until first bite” may not directly translate. Lets look at the results of another study(1):

So there you go, DEET all the way. An interesting item to note is that any repellent with over 25% DEET only makes the effect last longer not more effective at any given moment. That means there is little sense in drenching yourself in multiple coatings at once. It’s also interesting to note that one of the Lemon eucalyptus oil repellents seemed to do very well. The active chemical in that oil ( PMD) doesn’t seem to be as well tested as DEET. The effect doesn’t seem as reliable (depending on the brand). There are some concerns here about using a “natural” product, but it’s been noted that  DEET is not very good at travelling through your skin. It’s been deemed pretty safe if you use it properly.

Which brings us to the second major factor in bite prevention – Application. The way you use a repellent is almost as important as its active ingredient. Firstly one must consider there are safety aspects here – DEET is safe, but nothing is idiot proof. For one do not apply DEET under your clothing or on open cuts. It’s not a deodorant or disinfectant. Always avoid spraying it near your mouth, ears and eyes. To cover those areas spray some in your hand and rub the oil onto your ears or face to avoid irritation. You don’t want to get the oil inside of your body via mucus membrane: Don’t eat the DEET. DEET works best when applied directly onto your exposed skin. You are likely wasting the oil by spraying it on your clothing, but that is up to you. One last safety don’t is applying DEET within a half hour of applying sunscreen.  Some concerns have been raised that the chemicals in sunscreen which open your pores for it to be absorbed into your skin can also permit DEET oil to be absorbed. I suggest putting the sunscreen on at home and the repellent on at the trail-head.

One thing to note when applying your repellent is that Mosquitoes are generally ground dwelling creatures that wait in grasses or under leafs for a passing meal. Spraying your sock line and legs may help to more efficiently obfuscate the scent that constantly drifts downwards and spreads outwards from your body. Be sure to spray areas where you’ve been previously bitten (like the back of your arms) as bite patterns are not random. They always look for a sweet spot.

Switching to sweet scents (for a mosquito that is) it’s known that certain species of mosquitoes LOVE people’s dirty socks. This has something to do with your body odour (lactic acid, ammonia or ??) This human scent seems to really attract the disease carrying  Aedes Aegypti mosquitoes, but likely will bring other species to you. It’s been broadly thought that floral scents (like those in your laundry detergent) were attractants, but that is not always true. Some floral scents, like Victoria Secret(1) can repel mosquitoes. Compared to the floral scent, an effect that is much less in dispute is the “stinky sock” one mentioned previously. No doubt rarely washed armour and hydration bags come into play here. When in doubt risk the laundry detergent scent and wear clean clothes instead of dirty ones – Your friends will thank you!

Speaking of friends there is no way to avoid these pests, but you can reduce the quantity of bites by find a hot riding partner (mosquitoes are attracted by body heat (6)) that believes any ol’ Facebook post about some new age mosquito repellent and never washes their armour – Just don’t send them this one!

Remember, you don’t have to be totally unattractive just a little bit less attractive and when it comes to mountain biking more speed usually solves the problem. 🙂

Efficacy of Some Wearable Devices Compared with Spray-On Insect Repellents for the Yellow Fever Mosquito, Aedes aegypti

Fradin, M.S. and Day, J.F. Comparative efficacy of insect repellents against mosquito bites. New England Journal of Medicine, 347:13-18, 2002.

Comparison of Repellency Effect of Mosquito Repellents for DEET, Citronella, and Fennel Oil

Best Mosquito Repellent Guide: Get Rid of These Blood Suckers Once And For All!

NPR: What’s The Best Way To Keep Mosquitoes From Biting?


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