The yellow line along the side of the cat and the black dots make me think it's a cloudless sulphur.

Here's a picture of a sleepy orange cat -

{{gwi:521427}}

And here's a green cloudless sulphur - once they start eating yellow flowers, they turn yellow -

{{gwi:521429}}

Sherry

Thank you, Sherry for setting me straight. I do hope my cat grows up to be as handsome as the one in your picture. I'm curious--do the Sleepy Orange cats look like your picture throughout all their instars?

Yes, sleepy orange cats always look the same, green with a faint cream colored line down the sides. The only thing that changes is their size.
The chrysalis of a sleepy orange is always green, not green or pink, like cloudless sulphurs can be. The butterfly emerges quickly, no overwintering that I've ever encountered. That's probably because they overwinter as adults - duh! :)

Sherry