Mud, not blossom, often wins the butterfly lottery. Along riverbanks or on a hiker’s damp shirt, wings flicker in tight clusters while untouched flowers stand nearby, because the prize there is not sugar but salt.The blunt truth is that nectar is a lopsided deal. It is rich in sucrose and fructose, yet strikingly poor in sodium and trace ions, the very ingredients that fuel action potentials in ne...More