Bagrada hilaris, A New Imported Pest To Beware Of
Bagrada hilaris is an African pest that recently appeared in Southern California. It likes to feed on plants in the Cabbage (Brassicaceae) family. Better photos and some links here. Another informative link here.
If you see this bug, kill it. If you see one there's usually a lot of them. Sorry, but it is a pest of human food crops and is an exotic. Smash them if you see them. They are slightly similar to a ladybug, but if you are at all familiar with lady bugs, you'll be able to tell the difference.
They feed on the exotic Mustard that is often found on our local hillsides. I've found them under Alyssum, so I've been pulling that. Be warned.