Many many of these trapped inside the foyer on a hot day.
Pretty big (~1/4" or so), swimming by this algae.
Found tons of dead water boatmen on top of dark cars in the parking lot. Little or none on light-colored cars. They were literally dropping from the sky around us hitting the cars then roasting on the hot surface.
Apparently water boatmen migrate then drop to water. I'm guessing they're mistaking the dark cars for pools of water?