The fungus grows inside the ants and releases chemicals that affect their behaviour. Some ants leave the colony and wander off to find fresh leaves on their own, while others fall from their tree-top havens on to leaves nearer the ground.

The final stage of the parasitic death sentence is the most macabre. In their last hours, infected ants move towards the underside of the leaf they are on and lock their mandibles in a “death grip” around the central vein, immobilising themselves and locking the fungus in position.

“This can happen en masse. You can find whole graveyards with 20 or 30 ants in a square metre. Each time, they are on leaves that are a particular height off the ground and they have bitten into the main vein before dying,” said David Hughes at Harvard University.

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