San Pedro Cactus, Trichocereus pachanoi

A huge San Pedro Cactus, Trichocereus pachanoi, in full bloom.  The flowers open in late evening and close back in the morning, probably because it is pollinated by a moth, bat or other night flyer.  The bees, however, are taking advantage of the long Summer days to sneak in a two or three hour frenzy of activity just before the sun sets.  There was a huge swarm of bees taking advantage of some thirty or so flowers.  Luckily, they liked the flowers far more than harassing the photographer!