But Hughes and his colleagues chronicle the amazingly precise control the fungus has over its victim.

At a field site in a Thai forest, Hughes's team found that the infected carpenter ants are almost invariably found clamped onto the undersides of leaves that are 25 cms (about 10 inches) above the ground.

When the researchers placed leaves with infected ants at higher locations, or on the forest floor, the parasite failed to develop properly.

'The fungus accurately manipulates the infected ants into dying where the parasite prefers to be, by making the ants travel a long way during the last hours of their lives,' Hughes said.

Carpenter ants apparently have few defences against the fungus. The most important way they avoid infection seems to be staying as far away from victims as possible, said a Harvard release.

That may be part of the reason why these ants make their nests in the forest canopy, high above fungal breeding zones. Carpenter ants also seem to avoid blazing their foraging trails under infected areas.

These findings are slated for publication in the September issue of The American Naturalist.