An amazing, newly discovered bee species bores into solid sandstone and lays its eggs in it. These bees do not live in colonies. They are solitary, although they may eventually build many tunnels near each other. The bee has been found in Utah, southwest Colorado, and the Death Valley area of California.
The bees use their very hard mandibles to chew through the stone. Many of the older female bees of this species have mandibles that show significant wear and tear. The young bees that emerge from the tunnels apparently come back and lay their eggs in the same tunnels, and expand them.
No one knows how long it takes these bees to burrow into sandstone, but once a tunnel is built, it is much more permanent than the tunnels of bees that nest in dirt. Besides permanence, the tunnels appear to have other advantages. The tunnels harbor fewer microbial parasites than those in dirt, and they protect the bees from occasional flash floods better than tunnels built in dirt.