I don't think there's anything wrong with him/her. I've seen numerous cats, especially swallowtails, wait a while before resuming eating. There will always be individual variations in behavior with caterpillars.
Sherry

He's just trying to see how totally crazy he can make you, since he doesn't feel like eating right now.

hahaha, I think you are right fighting8r, lol, i swear they have figured out that if they wander enough, they get "better" leaves, and some seem to do so quite often, and raise up and start waving their heads around when i open their little boxes, like "where is the new leaf, hurry up" and he is making me crazy, i kept checking on him last night, haha. thanks missherry and fighting8r!!

he is still not eating, but what worries me is that it looks like he is trying to, and then gives up and wanders around some more, then does it again. I checked on him earlier, and he was hanging upside down in a ball from the bottom of the leaf, like he was stuck, and just dangling from his silk thread, he seems weak, i wish he would start eating soon. thanks

Hmmm....it does sound like there's something wrong with him, but there's probably nothing you can do about it. Don't worry - he may eventually eat.
Sherry

he nibbled just a tiny bit ( you can barely see the little missing pieces on the edges of leaf) and now he is just sitting on the leaf. he looks skinny, and weak, like his skin looks all baggy and wrinkly. but he did molt successfully, because I saw his old skin and head capsule. So strange, he was fine before the molt, and now it seems like he doesn't "like" orange leaves anymore and is looking for something else. I truly think something is wrong with his mouthparts, since he appears to at least try to nibble, then it is like he gets frustrated and starts pacing around again, his behavior is almost exactly like that of cats that are looking for a place to pupate. and he is about 3 weeks old, i think, the other two hatchlings from his "group" died when they were like two of three days old, one hardly ate at all, the other was eating normally and when I went to change his leaf and picked it up, he rolled off, i waited a while to see if he startedmoving again, but he died on the leaf. I guess it is survival of the fittest so to speak, even when they are indoors. I used to keep them separated according to size, but i decided to keep all of the cats in their own individual containers after I had one cat die when trying to molt, I am almost positive that the cat he shared a container with, ate the leaf he was attached to and knocked him off before he molted, even though he had his own new leaf, because he was fine when i checked them before i went to bed that night, and when i woke up he was lying on the floor of container trapped in his old skin, and the other cat was on the leaf eating it, they had shared a container since they hatched, but apparently this particular cat didn't like to share, he is one of the few I have that still "stinks" me when I change his leaf and clean his container, he is super aggressive, most of them seem to be used to me and don't get defensive when I clean and give new leaves, but this one almost EVERY time, sticks his little horns out at me, I dread fooling with his container because i cannot stand that smell, lol. I lost one more cat due to an unsuccessful molt, it was a first instar, not sure what happened but he was all tangled up in his old skin. But the first one I lost due to molting was on his 3rd molt, and completely healthy, so the only thing I could think of that may have happened was that the other cat forced him off of the leaf, but idk, I felt so sorry for him, all that work and time, and he had made it through the more delicate stages and survived.

Hopefully this one will perk up, I thought about putting him outside on the tree, it is nice and sunny today, and letting him wander around to see if he finds a leaf that suits him, I have some tulle fabric I can tie around the tree to keep predators from getting him, does that sound like a good idea? thanks everyone!!

Well, he finally decided to eat! I put his container outside for a little while and he just sat there in the sun for a while, I brought him back inside and he started eating like crazy almost immediately!! Who knows, do GST cats like to be in the sun? I guess it would make sense seeing as how citrus trees are one of their host plants. Anyway, not sure if the sun had anything to do with it or not but he perked up and seems to be back to "normal", these creatures are so strange, lol. I have about 11 cats that should stop eating any day now, and start looking for a place to pupate, I love it when they are at this stage, they will eat every leaf I give them, and even eat the rest of their old leaf before they start on their new leaf for the day, I am so glad that the majority of them have reached this point, makes my job a whole lot easier, ;-)