Leaf-cutter Bees are a family of solitary bee species, known for the female cutting neat segments from leaves and rolling them into a sausage shape, which they then use to make nest cells in a variety of cavities. This one is not doing its characteristic leaf-cutting. Most bees collect pollen in sacs on their legs, but leaf-cutter bees have a pollen brush under their abdomen, and you can clearly see the orange pollen from the sunflower.