|Organ pipe dauber nest|
|Black and yellow dauber nest|
The blue mud dauber Chalybion californicum is a metallic blue species that preys primarily on black widow spiders. It does not build a nest, but uses nests abandoned by other mud dauber wasps. It doesn't carry mud but only water which it uses to renovate their previously used nest. Like other mud daubers, it is rarely aggressive. Think about it- doesn't build new nests, doesn't attack and harvests black widow spiders. Sounds like a good household pet to me.
There is a summary of these wasps in the Discover Nature Field Guide.