Fly on yellow starthistle, Santa Clara County, California - Urophora
Los Trancos Open Space Preserve near Palo Alto, Santa Clara County, California, USA
May 29, 2015
Size: approx. 0.5 cm long
I originally thought this was a false peacock fly since they are usually dancing on the yellow starthistle buds this time of year, however, when I looked at the photo up close later, I was surprised that the thorax was solid black instead of spotted. Do they have a life stage or newly hatched form that has a solid thorax? Could possibly be the angle of the sun.