During the Croatian war of independence in the early-Nineties, more than 1.5 million land mines were laid across the country. Although the remaining minefields are marked, de-mining is not yet complete, and over 500 people have been killed and many more injured by land mines since the war ended.
Even once a field has been de-mined and checked, there is a chance that remaining land mines could still be hidden beneath the soil. However, Croatian scientists have developed a rather novel solution to uncovering the remaining mines: bees.
These insects have an exceptionally good sense of smell, which means they can be trained to sniff out trinitrotoluene (TNT) – the explosive used in these devices.
A sugar solution is placed into a glass to simulate nectar and this is placed in soil containing traces of TNT. As the bees fly towards their sugary drink, they smell the TNT and, over a period of three or four days, gradually learn to associate the smell of explosives with the promise of food.
Once the bees are trained, they can be transported to fields and released into the air. Bees are incredibly hard to track visually, but they emit a lot of heat as they fly, and so can
be followed with an infrared camera. Their small size also means that, unlike trained mine-detecting dogs, they are not at risk of setting off an undetonated mine.
The research has yet to be completed, but it is hoped the bees will be able to help confirm if fields have been properly de-mined.