The lazy temptation would be to just call this Bembix americana. But Bembix americana is, as far as I can determine, consistently black and white, not black and yellow. Bembix americana occurs in this location as well, and it looks different in more than one way. The mystery Bembix seems to have one more light stripe across the abdomen than americana, in addition to the color difference. Moreover, groups of the two do not seem to intermingle. On Point Wilson, for instance, there is one group in one section, and a group of the other type in another section. Several other Bembix species are known to occur in the Pacific Northwest, as listed at http://www.discoverlife.org/20/q. But virtually none are pictured on the internet. Any expert have an answer?