The smallest animal currently being trained to potentially detect land mines is the honeybee (Apis mellifera), which measures 12 mm (0.5 in) long. In August 2003, field tests led by researchers from the University of Montana, in cooperation with Sandia National Laboratories, S&K Electronics and Montana State University (all USA), noted a 98% success rate in tests observing the insects hovering in response to chemicals leaking into the air from buried explosives.The 98% refers to tests with chemical vapour concentrations as parts per billion. This becomes 95% with very low parts per trillion. The field trials have been in places like Fort Leonard Wood, Missouri, USA where explosives have been buried for years and are leaking. The team hopes to move to real fields soon. The hairs on a honeybee are such that they easily gather chemical and biological particles. Training the bees to locate the explosives is similar to techniques used to train dogs, that is being teaching them to associate a smell with a food reward (in this case sugar-water). The advantages of developing honeybees for this purpose are their cheap running costs and the fact bees naturally recruit other bees themselves and teach them.Pic: Alamy