Eurosta solidaginis

The goldenrod gall fly , also known as the goldenrod ball gallmaker, is a species of fly native to North America. The species is best known for the characteristic galls it forms on several species in the Solidago, or goldenrod, genus. The fly's eggs are inserted near the developing buds of the plant. After hatching, the larvae migrate to an area below the plant's developing buds, where they then induce the plant's tissues to form into the hardened, bulbous chamber referred to as a gall. E. solidaginis’s interactions with its host plant and insect, as well as avian, predators have made it the centerpiece of much ecological and evolutionary biology research, and its tolerance of freezing temperatures has inspired studies into the anti-freeze properties of its biochemistry.