One of my favorite phrases in Spanish is "por si las moscas" which is used the same way you'd use "just in case" in English, but the literal meaning is "for if the flies." So, you know, you'd want to cover up your cheese or bread or whatever so the flies don't get to it because you never know when they'll show up.
I like this expression not only because it's got a pronunciation that is very easy for a native English speaker, no trills or coronal fricatives or the other difficulties, but also because it is a connection, a reminder of a different, more pastoral time.
For me, and I'd imagine for most of you as well, flies don't really present much of a problem in our daily lives. Oh, sure, you'll encounter them out of doors and one or two will make their way into your house, but it's nothing that a fly swatter or, even better, a Bug-A-Salt, can't take care of without too much fuss.
In contrast, for those who did (or who still do in many parts of world) live both close to livestock and without the benefit of HVAC-sealed homes, flies are a whole other level of nuisance.
Growing up, at least in my early years, much of my family was involved in harness horse racing, so I spent a lot of time in hardscrabble living conditions very close to horses, and, well, the flies, oh my God the flies were omnipresent. And not just your everyday house fly by the mean-spirited, vicious, insatiable, horse fly with it's painful bite.1 That is a whole other world of flies.
And then there were the fly strips, sometimes so heavy with collected flies that you could no longer make out the brown-gold of the glue strip, and they'd hang from the ceilings of the barns and tackrooms loaded down with their black-bodied and diaphanous winged collection, swaying there in the fetid air of horse flesh, hay, grain, and manure like some Renfield-imagined elementary school arts & crafts project.
I enjoy these memories, but I'm careful to romanticize it. The flies remind me not to.
Meanwhile, if there's a chance of an afternoon, spring shower where you live, better take your umbrella, por si las moscas.
1 The only fly I've personally encountered with a bite worse than the horse fly of my youth, is the green head.