Scientists at the University of Wisconsin have discovered how a species of leaf cutter ant produces its own home-made antibiotics to keep fungal infections at bay in the nest. Leaf cutters are nature's gardeners. They crop green plants and carry the pieces back to their nests where they infect them with a fungus which breaks down the plant matter and is then, in turn, itself eaten by the ants. But just as weeds grow in even the most carefully tended gardens, the ants nests are threatened with invasion by a poisonous fungus, called Escovopsis, which the ants have to keep at bay. They do this by coating their body surface with a species of filamentous bacterium, called pseudonocardia, which provides the ants with an antibiotic chemical weapon with which to combact the invading fungus. Until now it wasn't known how the ants carried or nurtured their bacterial charges, but writing in this week's edition of the journal Science, Cameron Currie and his colleagues at the university of Wisconsin have discovered that the ants have evolved a special system of pouches, called crypts, each of which is fed by the ant-equivalent of a sweat gland. These provide the ideal home for the bacteria which take up residence and turn themselves into portable pharmacies, producing a cocktail of antibiotics which the ants can dispense around their nests. So it looks as though Alexander Fleming may have to surrender the crown for discovering antibiotics - these ants must have been using them for millions of years!