Today for #MarshMadness I have Osmia bicolor, a mason bee known for building its nests inside the empty shells of snails. Each shell can hold 4-5 cells, one egg per cell, which is constructed from chewed up leaves and provisioned with balls of pollen mixed with nectar. The snail shells are then sealed up with sand and gravel, partially buried, and covered with twigs and grass for added protection. #SciArt #InsectArt #watercolor