These Bees Excavate Their Nests in Solid Rock

Bee species “has pioneered a suitable niche between a rock and a hard place."

Members of a bee species discovered in the deserts of the American Southwest are by no means shoddy builders. Surrounded by loose, easy-to-dig sand and soil, they choose to excavate their nests the hard way — by gnawing into solid sandstone.

Entomologists were puzzled as to why the species, named Anthophora pueblo, was dead set on spending so much effort chiselling out homes in rock while less taxing options were readily available.

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Researchers knew where to search for the nests. "As the bees use water to help excavate the sandstone, we found many sites by targeting areas near water," Michael Orr, a doctoral student at Utah State University and lead author of a study published in Current Biology, says in a press release.

In this species, each bee lives alone in its own little alcove, but their dwellings are built in close proximity to one another.

The sandstone nests are tougher and sturdier than the other options, Orr explains, meaning in years when bees decide not to emerge due to low supply of blooming desert flowers, they are well protected.

The nests are also less prone to erosion, so they keep bees safe from flash floods, and the sandstone seems to deter the build-up of parasites, the researchers found.

Then there’s the durability of the nests, which enables the next generation to reuse the tunnels dug out by their parents.

All of these benefits do not come without costs though. The mandibles of older females that had spent their lives digging into stone were in bad shape, the researchers noted, and burrowing through sandstone takes a greater energetic toll on the bees than simply delving into dirt.

But, as the authors conclude in the paper, “the benefits of nesting in sandstone appear to outweigh the associated costs in this system.”

"The desert is a hard place to live," Orr says. "Anthophora pueblo has pioneered a suitable niche between a rock and a hard place."

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