And,
Gerris2.
Always nice when a friendly and attractive plant volunteers in the garden and this one is host plant to the Common Buckeye butterfly too, it says at that link to the database. Looks like a match to me.
I have a patch of Plantago Major that is also a Buckeye host plant but also considered a weed by most people. I've gotten so interested in butterflies I am trying to accumulate host plants for them so I am leaving that plantain (though I expect it's probably more thuggish than the Ruellia.)
