Cheryl, you raise a good question. One time I was visiting Grandma in WV in mid-April which is about the earliest I'd ever been there. I spotted a Variegated Frit in her yard and snapped a picture. That was Apr 14, 2011. I sent it to BAMONA and this is the note they added to my sighting: "This is a very early date for this species in WV. It is likely that this species does not overwinter in the state but immigrates in from the south." Seeing as how you are in PA, I would think that the same applies for you. I believe I read that some Fritillaries overwinter as an egg. The female lays eggs near violets, as you said, and they hatch around the time the violets start putting out new growth in the spring. This is something we should research.
Since you brought up frass...I forget you haven't heard all my stories yet. Good, because I like telling them.
So since frass is a giveaway for the caterpillar's location, and one I often use myself, it makes sense that some caterpillars have learned to hide the evidence. Spicebush caterpillars will put themselves into reverse gear, back up to the edge of the leaf, and poop off the edge so it falls to the ground. They're one of the few caterpillars I've seen that will walk straight backwards without making a turn. Super cool.
But even better, and funnier in my opinion, are Long-Tailed Skippers. I think some other Skippers have similar abilities. First of all, they are leaf rollers, so they build a shelter like the Spicebush. A little different shape, but same concept. I've seen them stick their tail end over the edge of the leaf to poop. But what's really amazing is that their anus has the ability to shoot the frass with such force they can expel it as far as thirty times the length of their body! I have raised them inside and when they get larger, I can actually hear the frass "pinging" off the sides of the plastic. I laugh every time I hear it. Especially when I'm in bed trying to fall asleep.