Eric, I'm so jealous! I'm always trying to get bumble bee pictures, but mine never come out so good as yours. Nice. Thanks. --Joolz

I can tell you that I have hundreds on my caryopteris shrub. They also like the heliotrope.

Putting it up at night certainly seems reasonable.

Those are bald-faced hornets, not to be confused with the yellow and black paper wasps, which are far more common and less aggressive. The hornets both bite and sting - they're pretty nasty - they defend their nest pretty aggressively, 10 years ago, my son kicked a soccer ball into a nest hiding in the shrubbery and we all got stung. I usually get one or two nests high up in a tree every year - usually don't notice them until the leaves fall. From mid-August until Mid-September, they can double their population and size of the nest. We quit watering the window box flowers 3 feet below this just as a precaution. I ended up emptying two cans of wasp spray on this thing, 3 days apart, and I think they've finally died off or moved on. After a freeze, the magpies demolish the nests and eat any eggs left. edit - got the wrong picture and don't know how to delete a picture. Top is the bald faced, below a yellow jacket.