I attach some pictures of different types of bees that enter the holes in the cob and that enter the stems. I made one ugly cob and stem block last week and the bees are starting to use it now. There are about 5 types of bees using the cob blocks. The wasp mimic uses it for shelter at night, a bee about the size of the orchard masons uses it for brood. A green bee seems to use it for brood. A tiny black bee uses some small and medium holes and a large brown bee uses it too. Today, 3rd august, tiny bees were swarming a little near the cob and stem block and a large bee used one of the front holes.