California Yellowjacket (Vespula sulphurea)

Appearance:

The California Yellowjacket has a half-inch long, stout body with yellow and black coloration. Like the Western Yellowjacket, it has a yellow "eye loop" or ring surrounding the upper portion of the eye. It can be distinguished from other species found in California by two yellow, longitudinal stripes on the thorax.

Habits:

As yellowjackets go, the California Yellowjacket is probably the most laid-back. It's not a serious stinging hazard, nor has it been reported as a picnic pest. This species is attracted to sugary secretions and preys on live insects.

Nests:

Most California Yellowjacket nests are subterranean, but they can also be found in logs and manmade structures. This yellowjacket species is not as abundant as others found in California and surrounding areas. 

Nature toward humans:

California Yellowjackets are not a serious stinging hazard unless the nest is disturbed.

Other Yellowjacket species

Paper Wasps

Hornets