What are these purple and white spots on the goldenrod leaves? They are caused by a bug, a goldenrod gall midge called Asteromyia carbonifera. The bugs carry a fungus (Botryosphaeria dothidea) that protect their larvae from parasitoids. The female Asteromyia lay eggs and deposit the fungus along with the eggs on the goldenrod leaves. The… Continue reading What’s That? May 20, 2025