Scientists in Turkey and Iran recently discovered a tiny bee that uses flower petals to build nest capsules. The bee, Osmia avoseta, uses only the petals of Onobrychis viciifolia for this important work.
I somehow missed this story, which was run by NPR on May 6, 2010. But it’s not too late to follow the link and see a fascinating series of photos by Jerome Rozen of the American Museum of Natural History. It is well worth a look.
The fertile female O. avoseta builds about ten of these petal nests in a cluster. The cluster itself is in the bottom of a thumb-size burrow in the ground. One by one she collects chunks of petals and laminates them together, cemented by thin layers of mud.
Once a capsule is complete, she provisions it with a mound of nectar and pollen and, like other Osmia females, lays a single egg on top of the provision. She then seals the open end of the capsule to protect it from environment dangers. Once the capsules are complete, the eggs transform into larvae and then pupae. The pupae spin a cocoon inside the capsule before eventually becoming adult bees.
The petal-donor, Onobrychis viciifolia (also known as sainfoin) is a perennial legume native to Eurasia. It has been cultivated widely for animal forage and is now found throughout the world. The flowers are pink, showy, and produce large amounts of both pollen and nectar, making it extremely attractive to many pollinators, including honey bees.