Nature’s Fairy (Brenda) is YouTube friend of mine in Bellingham, Massachusetts. She is very concerned about how Black Swallow Wort is taking over the landscape in her local nature spots and choking out larval food plants for the Monarch. Although Black Swallow Wort is not a problem yet where I live in SC, I wanted to spread the word by sharing her videos in the hopes that others in her region would help her control this plant.
Help Save the Endangered Monarch https://www.youtube.com/watch?v=az7To7h4NDg&t=1s
I found this informative guide about Black Swallow Wort elsewhere on iNat. Evidently it started in Massachusetts, but has spread to several states from there. https://www.inaturalist.org/guide_taxa/926682
Come to think of it I was thinking of V. rossicum - Pale Swallow wort, with the lighter colored flowers. But I think they share many of the problems such as being a Monarch sink, and it’s easy to learn them both at the same time. I haven’t seen V. nigrum yet but will keep an eye out. It looks like it is making inroads into PA.
Thanks for telling me about Pale Swallow Wort. I think I’ve seen it before when I was on vacation, I can’t remember if it was Virginia or Pennsylvania.