… because it helps them get laid.
Human blood is apparently some sort of horny-goat-weed for Lepidoptera apparently.
The story has been everywhere. Everywhere! Nothing could be more halloweeny than a vampire blood-sucking moth. Hattip is going to Zooillogix, cos I saw it there first.
The blood sucking moth does not digest the blood. Repeat: It does not feed on the blood. No actual haemophagy.
So it is very “transitional form” about it. The exact function for sucking blood is not yet understood. The “it’s to feed the babies” answer does sound a bit pulled-out-of-my-ass, but I’m not an entymologist.
Only male moths exhibit blood-feeding, she noted, raising the possibility that as in some species of butterflies and other moths, the Russian moths do it to pass on salt to females during copulation.
See it is all sex’s fault that nature does weird things.
Whatever the ecological motivation for the adaption is, it is very cool to be able to “see” an evolutionary stepping stone from a flower-feeding apparatus to one that can also suck blood (I’m assuming they are still eating nectar, right?).
Morphological adaptions do not start out being used the way they end up being used. Organs are co-opted, un-opted and re-opted to new and exciting purposes throughout the ages. Our ear bones were once jaw bones. Spider silk was originally developed as bedding insulation. And for all we know, we may actually be the a larval form of some unbeknownst higher being that lives far too long to ever reach metamorphosis. Oh yes. I just blew your freaking mind.