The Best Ultralight Solution to Insect Repellent (a case for DEET)
Over the last 2 years I have been messing around with how I use bug spray on trail. For years I was all about that DEET life.
Then I discovered both permethrin and picaridin. Permethrin is a god send and treating your clothing with it keeps biting insects from trying to bite or poke their way through your clothing. I don't hike in bug season without treated clothing. I use enough of it that instead of using the spray bottle I linked to above I actually buy a concentrated form of it and dilute it. This is more cost effective and a good guide for doing this can be found at Section Hiker.
Picaridin was wonderful too. I started using it in the spring of 2016. It isn't greasy like DEET and it smells much better. It doesn't smell good or anything. Just better. It also doesn't ruin any nylon based clothing or gear it happens to come into contact with.
But when I switched from DEET to picaridin I noticed something - I was using MUCH more picaridin in order to achieve the same results that I had with DEET.
Using picaridin I would need to apply much more of it to my skin and make sure it was evenly applied in order for it to work perfectly. I also needed to reapply every 2-4 hours depending on how much I was sweating. This resulted in burning through a 3 oz bottle of the stuff every 2-3 days in peak bug season. That's not light weight at all! Additionally the bottle is about 2.5x bigger than the DEET bottle I'd normally bring. This means it is harder to fit in a hip belt or shoulder mounted pocket.
The DEET I used was the 98.25% Off Deep Woods variety, which if kept in a small ziplock bag won't melt any nylon it comes into contact with. I can apply a much smaller amount pretty haphazardly without having to rub it all over my skin and it works for around 5-7 hours depending on how much I am sweating. This means I can carry much less of it in a smaller container and it lasts longer.
DEET isn't a perfect solution. It's greasy and smells and if you happen to get any on your lips or in your eyes it is unpleasant, but as far as ultralight bug repellent systems go the combination of permethrin for your clothing and DEET for you skin cannot be beat.