Answer: Grow Fungus

A fixture in nature documentaries and school science books because of their curious and industrious leaf harvesting efforts, leaf cutter ants—despite what you might have assumed—don’t actually eat the leaves.

The leaves are, instead, food for the ants’ elaborate underground fungus farms. Leaf cutter ants have a symbiotic relationship with strains of fungi in the Lepiotaceae family and have, for tens of millions of years, carefully tended underground gardens of fungus. The ants feed the fungus leaf clippings and, in return, the fungus flourishes and provides nutrients for the ant larvae in the colony.

The relationship between leaf cutter ants and their fungus is sophisticated, with the ants being able to detect tiny traces of chemical compounds secreted by the fungal colonies, which the ants use to adjust growing conditions and to tend to the fungus just like a farmer analyzing soil.

Fungus is so critical to leaf cutter ants that when a new queen sets out to form a new colony, she takes a starter fungus with her in a specialized pocket within her mouth to seed her new colony. In the photograph here, you can see a mature queen with her workers, seated upon a mountain of the fungus that sustains the colony.