Sorry, I suppose they would be a kind of pet. I am virtually sure they came from oothecas I purchased from a nursery supposedly to control aphids. They appeared months after placing the egg cases in the garden and I had assumed the hatching had gone bad. I guess not. However I now doubt the wisdom of this move as the only insects I have observed them eat have been beneficials, i.e. a spider, a bee, and a ladybird beetle. They have now produced at least two oothecas that I have found in the yard and I'm cosidering removing them from the system. I made the Chinese Mantis guess from looking a pictures on the web. I must admit they are amusing to watch. Also It is possible they have actually naturalized in So Cal as a result of the nursery bio-control thing.

Thank you very much for the clarification. I would have thought Californians would know better about immigrants of the insect sort, but then, considering who the governator is...LOL! Seriously, your explanation makes perfect sense. Very nice images, moving them to species page.