Accidental temporary hornworm parent—help?

I got a hornworm to feed to my tarantula, but she decided she wasn’t hungry. So now I have a bonus pet… At least until my tarantula is hungry again (sorry!). I’m having trouble finding detailed info on proper hornworm care, though. I read that they can eat potatoes and carrots (among other things), so that’s what I’ve been feeding it so far because it’s what I have on hand. Is it normal for the poop to be the exact same color as the food? Or does that mean there’s some problem with digestion? I’m also wondering how often they should be fed—I gave it a baby carrot last night, and it’s almost totally devoured it already. Do I just keep replenishing the food so there’s always some available? I’m adding a picture as well, so please feel free to provide enclosure feedback.