From Kingdom of Ants, by E.O. Wilson and José M. Gómez Durán:
The leafcutter ant trail pheromones, identified by twentieth-century elements, have turned out to be extraordinarily efficient in meeting the needs of workers when recruiting nestmates over long distances. The trail pheromone of the North American leafcutter Atta texana, methyl-4-methylpryolle-2-carboxylate, is extraordinarily potent. Entomologists have estimated that 1 milligram of this substance, which seems scarcely a trace to human beings but is roughly the quantity found in an entire colony, if laid out with perfect efficiency, is enough to lead a worker three times around the world. Even more impressive is the estimate that a milligram from the South American grass-cutting leafcutter Atta vollenweideri would suffice to lead a worker sixty times around the earth.