Land mines may set off little buzzers.

As a flower's scent lures bees to collect pollen, the aroma of TNT or other explosives might soon entice the insects to join a humanitarian mission against land mines. TNT, or trinitrotoluene, is the main ingredient of an estimated 100 million typically plastic land mines in the world that are a legacy of various wars. Each day, these hidden weapons kill or maim some 60 people.

Researchers at the University of Montana in Missoula and numerous U.S. government labs plan to start tests with honeybees later this month. They hope to determine whether it's possible to train and monitor the insects in ways that might lead to safer, quicker detection of land mines.

The Montana researchers had found that bees foraging in chemically contaminated areas accidentally pick up sufficient pollutants to reveal the presence of such substances within a half-mile or so of a hive (SN: 5/24/97, p. 324). Preliminary studies have since found that bees can bring home traces of explosives as well.

In the new tests, researchers hope to find out whether plants incorporate residues from leaky mines into pollen and nectar. They also plan to determine how much bomb residue bees might bring into hives from minefields and whether the chemicals taint the dust and pollen stuck to bee bodies, the fluids that bees ingest, or both.

Researchers will also try to train bees to seek out explosives by associating the compounds' scents with hives or food. To keep track of individual bees' comings and goings, engineers at Pacific Northwest National Laboratory in Richland, Wash., have shrunk electronic identification tags, readable via radio, to weigh less than a rice grain and fit on a bee's back. Another device, also to be glued on bees, may allow researchers to track the insects with hand-held radar guns, says Montana's Jerry J. Bromenshenk.

Similar techniques might also transform bees into scouts for illegal drugs or nuclear-bomb ingredients.

If the strategy works, "it's a cheap, nondestructive way to characterize a land mine site," says Susan Bender, leader of a group of researchers at Sandia National Laboratories in Albuquerque, N.M., that is involved in the project.

Nonetheless, convincing the people now clearing minefields to take up a technique "that frankly sounds a little farfetched" may bedevil the project, says Col. George Zahaczewsky, who runs the Pentagon office that oversees the U.S. military's humanitarian demining research.

In recent years, scientists around the world have been developing new mine-detection schemes, ranging from better sensors to bacteria that glow when they contact explosives (SN: 3/28/98, p. 202). Exotic approaches have been "poohpoohed by the demining community," says Zahaczewsky. Most deminers continue to find mines at great risk to themselves by cautiously prodding the soil with pokers.