Ojuice5001

They do not. They live for about a year as a swimming grub, then they turn into a fly, and then they live for a day. Why do people say that they live for only a day? Regarding beetles, mayflies, butterflies, and the like, the larval stage is really just as important as the adult stage.

If I died on the day after my 18th birthday, would people say that I lived only a day? No. It's the same way with mayflies.

sweep

that would depend on your definition of life and consciousness. It could also depend on the source of the information. Vicarious knowledge makes for distortions of reality in terms of available detail and understanding.

Rousseau_CHN

Interestingly, adult mayflies don't have mouth, and yet they have a fully developed stomach. But, like heck, if they are going to spend only one day in adult life...why even bother with a mouth...or a brain for that matter.

Undercurrent

It's because we have this odd habit with metamorphosing insect species, of giving the larval form a different common name than the adult. Not that much wierder than giving separate names to the genders of some species (bull vs cow, ram vs ewe, &c.)

seebs

Which is a shame, because if they really did live only one day, the "mayfly year" would be a very useful unit of time - about long enough to cook a pizza.