I've seen out of doors photos on other web sites stating that there were "hundreds of orbs" all around in the area where the photo was shot. I in fact have a similar photo I have taken myself on a camping trip. In my photo, there were orbs everywhere. Almost too many to count. What I remember about the time and place where I took the picture was there were mosquitos flying around us in swarms. Maybe many "orbs" are in fact light refracted off of the wings of flying insects as well.