I just love to observe the Summer Long-Horned bees Melissodes bimaculata.
Up until last month I had never seen any, and now they are every day in the garden, especially favoring the California Delta sunflower and Cosmos plants.
Their antennae are about twice as long as those of other bees, although they are smaller than honey bees. And they are responsible for pollinating plants in the Asteraceae family, including sunflowers.
These are images of the same bee.
In the top image you can see the pollen collecting on the bottom of the bee's abdomen, as it visits every blossom on one of the Cosmos Orange Sulphur Klondike plants.
Look at those long antennae.
Curled over all that pollen.