[Lee Stewart]

Look, but don't touch beetles of the family Meloidae. These beetles are popularly known as "blister beetles" because they secrete cantharidin, a toxin that causes — you guessed it — blistering. In fact, cantharidin can be beneficial, too: It's one of the active ingredients in wart-removal treatments. The compound, also known as "Spanish fly," is rumored to be an aphrodisiac, but it's more likely to ignite your intestines than your libido.