These colorful lesions were originally thought to be just fungal infections (Botryosphaeria dothidea) but were eventually found to harbor midge larvae (Asteromyia carbonifera) that farm the fungi for food and use the hardened hyphae to prevent (sometimes) parasitic wasps from ovipositing into the gall. In turn, emerging female flies dutifully transmit spores to new plants each generation. #goldenrod #fly #diptera #fungus #fungi #mutualism #gall #galls #solidago #cecidomyiidae #insects #entomology