Full Text (PDF).

This is a useful resource for California and beyond as it has a keys to:

1) the genera of Bembicini of North America;
2) the species of Bembix in California;
3) the 10 species of Bicyrtes in North America;
4) the 7 species of Microbembex in the continental US.

Note: This reference does not cover subtribe Stictiellina (i.e. genera Glenostictia, Microstictia, Steniolia, Stictiella, and Xerostictia)...which are covered in the later companion volume Bohart & Gillaspy(1)(1985).

[Caveat: I'm an amateur and can't competently comment on how much change may have occurred in Bembecine taxonomy since this publication in 1971. But, shortly after posting the above, I found a reference discussing at least two California species not known in 1971: Stictiella villegasi described by Bohart in 1982, and Microbembex elegans described Griswold in 1996. Bohart's 1982 paper included 4 other new Stictiella species outside CA as well. So there has been progress, and thus the work referenced here must be seen in that light. In particular, it is no longer complete for California taxa.]