Gray Tree Frogs- baby- just larger than a japanese beetle.

Q number 1- i was considering ordering rice flour beetle culture, but not sure if the baby gray should eat the larvae or the beetle itself. the beetle is actually smaller than it's larvae, and my frog is very small yet. he is eating melanogaster FF, but i do not think i like working with the FF.

Q number 2- Some people use a substrate on the floor of their enclosure. Is impaction a problem? do Gray tf accidentally eat substrate while hunting and if so, are they able to spit it back out? I am concerned about this for the future. baby won't have substrate for a while( except maybe damp paper towel. )