This shows a goldenrod gall fly, sitting on the goldenrod gall it just recently emerged from (there was a second fly from another gall). These small flies, in the Tephritidae family, spend the winter in the round goldenrod galls that are such a familiar part of our landscape in Ontario. The larva eventually moves from its snug nest in the middle of the gall, to a position close to the surface. There it begins the process of transforming into an adult (fly) and using an enlarged bulbous growth on its head, pushes its way out. The hole from which it emerged is tiny compared to the size of the fly. The gall is also amazingly hard. I need a knife to cut it open, yet this little creature can push its way out!

I brought these galls home in April and kept them in a jar, waiting for the flies to come out, which they finally did today. I released them onto a patch of goldenrod in my yard.