The biggest is the Valley carpenter bee, Xylocopa varipuncta. It's about an inch long. The female is solid black, while the male, commonly known as "the teddy bear bee," is a green-eyed blond. Why teddy bear? It's fuzzy and does not sting--or as Thorp says "Boy bees don't sting."
The second largest is the California carpenter bee or Western carpenter bee, Xylocopa californica, often found in the mountain foothill areas of northern and southern California. It's known for its distinctive distinctive bluish metallic reflections on the body, Thorp says. The females have dark smoky brown wings.
The smallest is the foothill or mountain carpenter bee, Xylocopa tabaniformis orpifex. The females are black with light smoky-colored wings. The male has bright yellow marks on the lower part of its face and some yellow hairs on the top front of its thorax.
Ian