Citheronia bellavista

I just got some larvae of Citheronia bellavista and put them on some Sumac (Rhus). I live in Canada so the tree is staring to turn red. The caterpillars haven't eaten in 3 days but I'm not sure if it's because of the fact that the tree is turning red or if it's because they are still full from eating their eggs. If someone could give me any kind of answer to this it would be greatly appreciated.

Thank you very much for the info. I really hope this works because I cant wait to see the fifth instar larvae.

do you think that ligustrum vicaryi will work as well?

I tried it and they have started to eat it. Thank you very much for your answer.