What do bees need to survive? What makes them stay in a given area? Most people know that they need food, which is what flowers are for. Flowers provide bees with pollen (protein) and nectar (carbohydrates) resources. But, is this it? Do they only need food? The answer is no…bee’s also need other resources, like materials for building and maintaining nests. There are several types of materials that bees use to coat the inside of the nest or cap off the entrance once they are done filling the nest with eggs. One common material that some bees use is mud.
The bees in the photo are blue orchard bees (Osmia lignaria). They are cavity nesting bees, meaning that they nest in above ground cavities like dried stems or empty beetle holes in wood. They also use mud to create chambers between eggs, so each egg will have his or her own little compartment to develop in. You can see and example of the chambers here.
Female bees will gather in places where mud is abundant and dig and dig until they gather some mud and roll it into a nice ball.
She will carry the mud ball in her mouth, fly back to her nest, and that is when the construction begins. She will stay at the nest molding the mud to place it where and how she wants it. She will fly back and forth as many times as she needs, until she is done. Once the nest is filled with eggs, the bee will need to close the entrance of her nest to keep intruders out. She will fly back and forth until the entrance is sealed to her liking.
I will post about the other types of materials that are used by bees in future posts. But, remember to keep some patches of mud in or near your yard. It does not have to be a big patch, but having some accessible mud will make your yard more attractive to native bees.