Bees can detect explosives.
Entomologists (bug scientists) have known that bees can detect different kinds of dangerous chemicals, but research at the Los Alamos National Laboratory has shown that they can be trained to detect explosive materials!
The way you can train bees to detect explosives is to mix the explosive chemicals with sugar water. In a laboratory, when bees approach sugar water they have the same reaction that they have to flowers: they extend their proboscises to suck out the nectar. Doing this repeatedly with explosives and sugar water will cause the bees to associate the scent of the explosive chemicals with nectar. Bees trained in this way are actually more reliable than a lot of man-made equipment at detecting the explosive TATP, the same explosive used by American al-Qaeda terrorist Richard Reid and likely the explosive used in the 2005 London train bombings.
(source)


