Specially-trained “sniffer bees” are being put to work finding unexploded mines in the Balkans.

The unlikely insect heroes are being trained by Croatian researchers in a multimillion-euro program to sniff out the deadly landmines that are a legacy of the region’s 1990s war.

Zagreb University professor Nikola Kezic said industrious honeybees, with their perfect sense of smell, offered a surprisingly simple solution to the issue.

In an experiment, conducted in association with Scotland’s St Andrew’s University and codenamed Tiramisu, the bees are being trained to associate the smell of sugar syrup with TNT.

“The bees can clearly detect this target, and we are very satisfied,” Professor Kezic told news service Science X.

To train the bees, scientists set up feeding points, some of which contained TNT particles. These feeding points offered “a sugar solution as a reward”, he said.

“It is not a problem for a bee to learn the smell of an explosive, which it can then search,” he said. “You can train a bee, but training their colony of thousands becomes a problem.”

Dr Ross Gillander of St Andrews University designed the equipment that measures whether the bees are returning to their hives with traces of explosive. He was in Croatia for the latest round of field trials in April.

Dr Gillander said the bees were trained in the same way dogs would be.

“Basically we teach them by a version of reward, like you do with dogs,” he said.

“The bees fly out of their hive to go about their normal day-to-day job of finding pollen but instead of finding pollen they find explosives. It’s the sugar syrup that draws them out. The training takes two days and is much faster and more efficient than training a dog.”

Drone footage is used to pinpoint the bees’ finds, so mines can be cleared.

We will not be a country in peace until this problem is solved

Early trial results are promising, offering hope for the Balkans and other regions of the world where mines are a deadly issue.

Officials estimate 90,000 landmines were used in Croatia during the four-year Balkans conflict – mostly laid without maps or other location details. Landmines have killed about 2500 people in the area since 1991 – and maimed many thousands more.

Dijana Plestina, the head of the Croatian government’s de-mining bureau, said mines represented a large obstacle to people and industry, including agriculture and tourism.

“While this exists, we are living in a kind of terror, at least for the people who are living in areas suspected to have mines,” she said. “We will not be a country in peace until this problem is solved.”

Scientists say the bees could prove more effective than sniffer dogs in some circumstances because they can work for longer and are cheaper to use. But the winged life-savers do come with complications of their own – including a tendency to shirk off after a while.

“After three days the bees realise that they aren’t getting a reward from the TNT and, as a result, are uninterested in it, and [they] look for other things,” Dr Gillander said.

“After three days we have to re-train the honeybees to detect the explosives.”

On top of that, they won’t usually work when it’s wet or dark.