Yellow-Faced Bumble Bees, Bombus vosnesenskii, have been constant visitors in our garden ever since early spring.
I don't remember seeing so many of them throughout the summertime. Usually they are the first native bees that show up in the spring, and then we don't see many of them after mid-summer.
In the morning they are the first on the scene, such as this one on a Blue Thimble, Gilia capitata, flower head.
These bees are considered important pollinators for agriculture, and they certainly have been hard at work pollinating our tomato and strawberry flowers.
We have other native bees in the garden, as well, including Leaf cutting bees, Summer longhorn bees, carpenter bees, digger bees, Western honey bees, California bumble bees, and Black-tailed bumble bees, Wool carder bees, as well as flower flies.