X2 and handpick a large group of the smallest larvae you can find from your colony, let these young ones do the job. The larger larvae and beetles are simply too strong for this kind of material. They will eat the cartilage/bone and move the whole skeleton around way too much. Don't expect it to be done over night, rather take your time so you can keep an eye on the process. Rehydrate if necessary and replace larvae that have become too big for small ones. And good luck!
