Been using it for a while myself
NeemAura sells it on the web. Add one dropper full to each sprayer of natural fly spray. I use CLAC. I also add 15 - 20 drops of Pennyroyal to this. Yes, neem smells, do NOT get it on you…gack! Think of burnt garlic and faint skunk spray. … at the same time.
I also have mizxed up the CLAC and FLicks and added Neem to it this year and that seems to do a really nice job.
Neem Aura makes a good human spray that works really well on trail rides to keep those gnats at bay. I sometimes use it on the horse’s crochet hats when the no see ums are particularly bad…after I spray my helmet with it.
I also have the metered sprayers and use the breethease spray which is a menthol eucalyptus spray and it rocks on the gnats. My draftie will go stand under the sprayer when it’s really bad.
You can also use neem oil to repel garden pests (not so sucessful for me) and it is used for a whole array of things… do a web search… my favorite is that it’s used for birth control in some countries… Well, sure I see how the smell might just be a buzz kill