Goldenrod gall fly

Eurosta solidaginis is in the order Diptera and the family Tephritidae. The Tephritidae are commonly referred to as fruit flies, a common name they share with the Drosophilidae family. Two subspecies exist: E. solidaginis subsp. solidaginis and E. solidaginis subsp. fascipennis, distinguished morphologically by differences in hyaline regions of the wing margin. The former subspecies can be further subdivided into two host races, one of which forms galls in Solidago altissima and the other in S. gigantea. ==Distribution==

Eurosta solidaginis is widely distributed across the United States, ranging from Washington all the way to the eastern seaboard. The two subspecies occupy different ranges, with E. solidaginis subsp. solidaginis being found from the east coast to Minnesota and the Dakotas, up to the southeastern provinces of Canada, and down the southern border of the United States. E. solidaginis subsp. fascipennis, on the other hand, can be found as far west as Washington and as far east as Minnesota. ==Behavior and ecology==

Adult E. solidaginis emerge from their galls in the spring, with the males emerging prior to the females. The flies proceed to mate on goldenrod plants, and the females use their ovipositors to insert fertilized eggs into the buds of the goldenrod. Instead, the larva itself has robust freezing tolerance. The larva feeds on the tissues of the gall and molts twice before excavating a narrow exit tunnel out of the gall in mid-September. The parasitic wasps Eurytoma obtusiventris and E. gigantea also target the gallmaker. The former injects its eggs directly into E. solidaginis larvae prior to gall formation, whereas the latter oviposits into the gall itself. M. unicolor typically kills the E. solidaginis larva inhabiting the gall, but this does not appear to be an essential part of its life cycle. on the head ==Physiology==

The ability of E. solidaginis to survive the freezing temperatures of winter has been the subject of much research. In response to dropping temperatures and the senescence of surrounding plant tissues, the larva begins to synthesize and accumulate sorbitol and glycerol in its tissues. These compounds help protect the larvae against freezing damage by lowering the melting point of their bodily fluids, thus reducing the amount of ice that can form. Aquaporins, membrane proteins involved in the channeling of water, have also been shown to play a key role in E. solidaginis’ freezing tolerance. As ice forms in the larva's bodily fluids, solutes in the unfrozen liquid are concentrated, creating a strong osmotic gradient. In species like E. solidaginis that can channel water quickly enough in response to this freezing stress, water rapidly travels to the solute-rich extracellular environment, switching places with cryoprotectant molecules like glycerol, thus protecting the larva's tissues. Upregulation of these aquaporin proteins in the winter seasons corroborates the hypothesis that they play a key role in freezing tolerance. ==References==