These hundreds of tiny holes spread across a sandstone cliff wall in Utah’s San Rafael desert were made by a previously unknown species of rock-excavating bees, discovered 40 years ago but not reported in scientific literature. This bee, Anthophora pueblo, is named for the Puebloan sandstone cliff dwellings that dot the deserts of the southwestern United States.

Anthophora pueblo use their mandibles to chew away at the sandstone, creating a network of tunnels. The bees also munch tiny pockets into the rock in which to gestate and nourish young bees. A source of water is essential to the bees: The bees collect water and use it to weaken carbonate crystals that make a cement between the grains of sand.

It’s unusual for an insect to use water to excavate in rock, and it takes a lot of energy to carve tunnels through sandstone, but the same durability that makes it harder to excavate in sandstone is actually providing benefits. For instance, durable sandstone protects the bees from flash floods or heavy rains.

Another benefit is protection from parasites. As bees fly from plant to plant, they accidentally pick up larvae from parasitic beetles and carry them to their nest. Sometimes the larvae end up in a nest cell. But because adult bees build hard sandstone lids over each nest cell, the beetle larvae can’t get out again. Although the resident hatchling bee succumbs, the rest of the nest is spared because the trapped beetle larvae can’t grow and reproduce.

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