Killer Bees.

New Scientist reports on the latest weapon in the war on Colony Collapse Disorder, the syndrome that’s killing off thousands of beehives and potentially threatening agriculture as we know it. It’s a weapon in a metaphorical sense – actually, a\n acoustic sensor that detects things going on inside beehives – but it really does have the Department of Defense interested, because…

… honeybees also produce specific changes in sound when small amounts of toxicants are present in the air.

In other words, they make perfect little biochemical alarms.