It looks like a tobacco budworm to me. These caterpillars come in many colors, and, according to David Wagner, they 'end up matching the color of their foodplant' so I'm guessing this one has been eating another flower before it traveled to the pink hibiscus. Or maybe it was eating deep inside the bud where it was pale green. These caterpillars are closely related to the familiar corn earworm. Cotton is second in the list of common food plants, and cotton and hibiscus are in the same family of plants, so it figures. I've never raised any gray hairstreaks, so I had to look them up, too, in my Wagner book. He didn't say whether they ONLY eat flowers, but he says that's where to look for them, and the picture in the book is of a cat on a flower. The mallow family is listed second as a favorite food plant, and hibiscus and cotton are in that family. I assume they eat flowers exclusively, but I'd offer it some leaves, just in case. Nice finds! Sherry

It's up to you whether you want to bring them in or not. Unlike Monarchs, Black Swallowtails can overwinter as a chrysalis. So, they might not emerge until next year. They are susceptible to predation, though. I visited my SIL and found two late-instar cats on her parsley. I brought them home, mostly because she isn't an outdoor type person and wasn't thrilled to have something eating her cooking herbs. I'll feed them until they pupate and then put them in a protected spot outside. Martha

Still black swallowtails. Maybe you could just place a mesh, pop-up laundry hamper over the parsley and weigh it down with bricks or something. I don't know how well parsley holds up in a water pick or left overs container (with holes punched in it) like we usually use. If it droops immediately in water it wouldn't do. Sherry

Prolegs on segments A3-A6 and A10 with hump on A8 possible characteristics of early-instar sphinx moth caterpillar. You would need to research if any feed on roses.