A cleptoparasite in the bee hotel

The Red Mason bee is well over in the garden. They have been replaced by their smaller relatives, Osmia leaiana. They have started nesting in the bee hotel and there are several females stocking their nests with nectar and pollen and sealing their nests with chewed up leaves. I removed the side panel of the nest box temporarily to see the progress of the nests. Below is a female with a clump of chewed leaves starting another cell. The yellow lumps are the food supply necessary to nurture one…

Source: BugBlog