When I first tried framing this glorious female in the viewfinder I thought she was defecating, so I didn't realize until reviewing my pics that she had actually been exposing the pheromone glands on her ovipositor - see the close crop of her rear in my 2nd photo: the gland area is the wider ring halfway between the row of elongated abdominal scales and the brushy-fringed ovipositor valve/tip. After she repositioned to another Isocoma plant. I was again struggling to frame her - and then an enterprising male buzzed by my ear and immediately seized his opportunity! He's on the right in the 4th photo.