Honeybees are natural-born sniffers with antennae able to sense pollen in the wind and track it down to specific flowers, so bees are now being trained to recognize the scents of bomb ingredients. When the bees pick up a suspicious odor with their antennae, they flick their proboscises — a tubular feeding organ than extends from their mouths.
In practice, a honeybee bomb-detection unit would look like a simple box stationed outside airport security or a train platform. Inside the box, bees would be strapped into tubes and exposed to puffs of air where they could constantly check for the faint scent of a bomb. A video camera linked to pattern-recognition software would alert authorities when the bees started waving their proboscises in unison.