I’ve posted about the different nesting habits of bees before, but here’s a new kind of bee nest that I’ve recently learned about. There’s a group of Megachilid bees in Israel that nest inside abandoned snail shells! These bees belong to the genus Osmia, known as the mason bees in North America.
Here, they nest inside reeds or cavities; they build a nest cell, provision it with a ball of pollen, and lay an egg on the pollen ball. They wall off each nest cell with mud (hence the name).
The shell nesting Osmia bees of Israel also wall off their nest cells with mud, but instead of building them in reeds or tubes, they build them in snail shells.
Here is a video (by Nico Vereecken) of a shell nesting bee, Osmia sybarita/ lhotelleriei:
The climate is very hot here, so she has to move the shell into the shade and then bury it. Here’s a video (also by Nico Vereecken) of a female O. sybarita burying a shell:
These bees will also camouflage the shells by covering them with bits of grass and moss.
I learned about these Israeli bees recently, but as it turns out, there are many shell nesting Osmia bees, including a species in south England (Osmia bicolor) (there’s a cute video in that link too). There’s also a BBC radio spot on them.