We've been using natural/chemical-free products on ourselves and in our home for the better part of a decade so when it was time to whip out the fly spray for the horses this summer I couldn't bring myself to use the typical store-bought stuff. First, I always try to use natural options for our animals whenever possible but second (and even more importantly), if you've ever fly sprayed a horse or livestock you know that stuff ends blowing around and getting all over you, too...and I'm not a fan of the idea of commercial insecticides getting all over our skin, in our eyes, etc. 

I played around with a "recipe" a bit until I came up with one that I was really happy with. It works well, smells GREAT and is economical. Apple cider vinegar is cheap and you can even by it by the gallon to save even more. A 15ml bottle of Terrashield is only $10.50, which will make you 2 batches of this spray and then you just need 20 or so drops of the other oils, both of which are also inexpensive. If you're used to the store-bought fly spray brands where 1 application will last you a full day or even a few days, just a heads up: there's not really anything natural that's going to give good results that are that long-lasting. Like I said, this is super effective but without the chemical insecticides you'll need to apply it a little more frequently than you would the toxic stuff! 

When it comes to DIYs I'm in the camp who usually doesn't measure anything and eyeballs everything but I know many are intimidated to whip stuff up without an actual recipe in-hand....if that's you, I hope this helps! I promise, you cannot mess this up!