On Valley Oak (Quercus lobata).
Sunning on a log with a couple of Red-eared Sliders. About the same size, maybe a bit bigger.
According to the sign, these abundant and regularly-spaced knots on the branches of California-grown quince trees are bacterial galls. Found an old book describing them and saying the cause wan't well-determined yet:
Lots of these in the zinnias.
Going nuts in a California Poppy. Really pollen-y abdomen underside.
On a zinnia.
Multiple bees per dahlia flower.
A few of them going in penstemon flowers.
Sold widely as an excellent nectaring plant... I find that it demands a lot of water or it will promptly wither; and sadly, doesn't really seem so attractive to local butterflies. Perhaps others have had more luck.
Torn & tattered.