Something is up with my beetle grub....

Hello guys why is my beetle grub turning orangish in color and it stopped eating and it just lays out of the substrate and its curled into a c shape but its still moving its mouth parts and legs. My grub never did this before... i had it for a few months already maybe ummm like 7 months.... its favorite food is fish food but now he isnt eating anything and his abdomen becomes thinner.... What's happening to it!!!! i spray the enclosure thrice a week , fed it fish flakes , rotting leaves , and logs. Is he pupating or something? will post pic tom.

I think...and dont hold me to this...I think he is pupating from what I've seen with my grubs but i dunno, species ID may help a bit...

I think its a rose chafer , but im not sure.

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