I thought, they might be thinking of mayflies, which have lifespans ranging from mere minutes to a handful of days.
I don’t know, if it’s a thing in other languages, too, but in German, we also happen to call them one-day-flies (“Eintagsfliegen”), which has kind of led to the myth that they live quite precisely only one day.
House flies live several weeks. I think you’re confusing fruit flies, which have a much shorter lifespan.
I thought, they might be thinking of mayflies, which have lifespans ranging from mere minutes to a handful of days.
I don’t know, if it’s a thing in other languages, too, but in German, we also happen to call them one-day-flies (“Eintagsfliegen”), which has kind of led to the myth that they live quite precisely only one day.
But turns out that mayflies do not look like that at all: https://en.wikipedia.org/wiki/Mayfly