A sand fly is a tiny sort of flying pesticle. You may be familiar with gnoths, buzzits, weetzles, lorcrusts, flittersnips, nose-buggers or skitter-midges, but sand flies are worse.
The sand fly (or "sand flea" as some call it) is the sole member of its taxonomic family, because it, through its absolute intolerability, drove all the other minute demons out of the club.
These guys fly, they bite, and they suck blood. Had enough? Well they haven't. They are also known as sand gnats, no-see-ums, chitras, punkies, and granny nippers. New Zealand has some too, as do other places, so you may get away, but only temporarily. They'll always find you in the end, no matter where you are, most likely when you have your pants down.
If horse flies are large enough to carry off horses, then sand flies are only big enough to carry off useless bits of sand. A horse does make a decent meal, especially for a fly, but sand? No. So what do you suppose that a sand fly feels when it alights atop its nest and prepares to dine, only to discover that it has brought home but a single grain of sand? Pure, mortified fury, that's what.
Which is when it heads for the nearest critter with a pulse, warm blood, a modicum of pit-stink, and rips into it. And "it" could be you.
Hah! So what? They're little bitsy things eh? Well sand flies may be tiny but their bites leave large blotchy itchy red bumps that merge into acres of fulminating rash. Yeah — that's right — fulminating. Not usually all that entertaining if you're the one providing the stage where this drama plays out.
How to tell if there are sand flies in your area: They are biting you.
How to find them: Go outside and wait. They will find you.
What to do if you are bitten: Howl. This doesn't help, so try something else — anything. That won't help either but go ahead anyway.
How to defend yourself against sand flies: Get yourself a pair of pinkle shears. Use them to clip (or "pinkle") the wingtips of any sand flies that come near you. (This is usually ineffective because sand flies are so small, and generally smarter than us, and flit around ever so fast in that peevish, buzzy way of theirs.)
How is this supposed to help? Well, any sand fly without wingtips immediately loses its flight certification and has to go hide in the bushes, but since they can still crawl around, they'll come at you later, after you're down there on the ground trying to sleep, so shucks. And you need exceptionally tiny hands to operate the pinkle shears, which is maybe OK if you're a dollhouse princess but not so likely if your name is Big Ed Merkel, and you have hands the size of smoked hams.
If the wingtip clipping is not a help to you for whatever reason, you can try preventing sand fly bites by using DEET-containing repellents on your skin and by wearing permethrin-treated clothing. Unfortunately for most of us, the results of these methods are iffy, the only sure-fire method being fire, as in setting yourself on fire — 100% effective but known to have unpleasant side effects, sometimes even worse than what happens when using DEET and permethrin, though a drop of each in a shot glass of vodka makes an intriguing sort of drink, and fire does not, of course.
But before you get all the way out on that particular limb, try home remedies. After all, you're desperate, right?
Option #1: Sprinkle eucalyptus oil on your clothes. Couldn't hurt, could it? (This also attracts bears, who are interesting in their own right.)
Option #2: Blow up a few balloons, rub them on the cat, and then watch as it tries to shake them off. Probably good for a few laughs while you lie there writhing in agony from sand fly bites, though doing this is likely to annoy the cat. If the cat is one of those big tawny jobs that you see dragging deer around by the throat, then yeah, you're probably gonna see some attitude.
Option #3: Rub yourself down with avocado oil, banana peels, vinegar, lavender oil, tea tree oil, or garlic, all of which might repel sand flies. If this sounds complicated, then just slip a key lime pie down your shirt and moosh it around. Take some selfies and post them so we can see.
So there's hope then? No.