Hercules final labor was to capture Cerberus, the three headed dog that guarded the underworld. Hercules got permission to take Cerberus from Hades, but Hades told him he could only have him if Hercules subdued him without using any weapons.
Under the Microscope: "The Adonis blue butterfly is rare because it's choosy. It lays its eggs (like the one above) only on horseshoe vetch, a European perennial. What's more, it looks for patches cropped by rabbits that allow easy landing.