Can't say that I've ever noticed it as a good nectar source for lepidoptera, but it is a larval food plant for some of the Chlosyne species.

I'm in PA also. I had Rudbeckia hirta planted here but never saw any butterflies on it at all, so I ripped mine out. I didn't like that it was so invasive either. It was here anyway.
Cathy

I'm also in PA. I have 'Goldsturm' in my garden (Rudbeckia fulgida var. sullivantii 'Goldsturm'). It blooms well, but no butterflies. It's a huge disappointment in that regards, so all but two were pulled and are being replaced this season with something more butterfly friendly.
Kim

I have Rudbeckia, don't know the variety. I get Silvery Checkerspot larvae on mine. I don't see any BF activity, but I planted it as a host plant.

Thanks everyone. We have Silvery Checkerspot (Chlosyne nycteis) in our area. I see it occasionally flying around the yard, but never thought to look for caterpillars on the Rudbeckia. I also have the host plants of sunflowers and wingstem (Verbesina alternifolia) that it is reported to use.

The American Goldfinches eat seed from the Rudbeckia Hirta seed heads in the winter and knock alot of the seed over the yard. (plus I've mowed some down which probably did more to spread it) I have soil that I imagine is 99% clay so black eyed susans are coming up all over. I'll take a look this summer for the caterpillars.

I've read that the Rudbeckia Hirta is drought tolerant, and although they seem to survive, they don't live very long. I had some come amongst my swamp milkweed before I added mulch, and they just grew and grew. I tried cutting them back, since I didn't want to disturb the milkweed roots by attempting dig or pull them up. Rather than slow them down, they only branched 10x and wound up with just as tall but bushier. I guess, what I'm trying to say is that it's drought tolerant character is often mentioned, but I've never seen it mentioned how well they perform with regular watering, and even pinching.

As I recall the only times I've seen butterflies at the flowers, they were visiting the larger of the flowers. ~ I wonder if the plants need to be regularly watered to get the large blossoms in order to attract butterflies. I've seen this with my Cosmos Bipinnatus, that the butterflies seem to ignore all but the largest blossoms.