Here is a Mentzelia decapetala (yes, folks, it really does have ten petals as advertised, although 5 of them are probably staminodia masquerading as petals - like you care...). The blossoms open up around sundown and stay open until midnight. The literature speculates that pollinators include bees and even ants, though it seems that any self-respecting such bugs would be long in bed. I suspect moths.
Whatever, this one looks pretty ravaged by last night's mating frenzy, but she is ready for another go. Her sweet perfume is making me dizzy; I have a sudden longing for wings and funny fuzzy antennae.