Courtship by Scent

Many animals advertise for a mate using pheromones — chemical signals carried on the wind. The male silk moth is the celebrity of this world. His feathery antennae are coated in receptors so finely tuned that a mere handful of female molecules drifting downwind is enough to set him flying upwind, tracing a scent plume no eye could ever see.

Some orchids hijack this system. They brew a scent that copies a female wasp's pheromone so convincingly that males land and try to mate with the flower. The wasp leaves with nothing but a dusting of pollen on his back, which he carries to the next fake female. Evolution turned sexual deception into a free pollination service.