Lorenzo L. Love said:

Record breaking warm weather has bought out the cabbage worm moths early
this year and I really need some Bt insecticide but I'm all out and the
only local store in town that sold Bt closed last year. A check of my
garden catalogs and a Google search don't show any good mail order
sources. Any recommendations for an on-line supplier for Bt spp. kurstaki?

You might try Territorial Seeds. (They are in Oregon so maybe they can
ship Bt to California -- they don't mention a restriction on their web page.)
Product # ZIN480 Dipel - Bacillus Thuringiensis

http://www.territorial-seed.com
--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)