I let a bunch of this grow outside my back gate. It is usually considered a weed, but it also listed in many wildflower databases. I like the little pink flowers and the way the stems turn red after a while.

But this year, I also noticed that the JB love to mate on it. Apparently, it's like a Poconos hotel room with a heart-shaped hot tub, for Japanese Beetles. I am always knocking pairs of beetles off in to my Soapy Bucket of Doom.

Maybe it keeps some of the little buggers from flying deeper into my yard? I notice the furtherest rose seldom gets JB, unlike the one near the back gate, where even the hint of a bloom lets me knock off a dozen bugs at a time.

Anyone else notice this?

Pennsylvania Smartweed - Polygonum pensylvanicum

Here is a link that might be useful: More about Pennsylvania Smartweed