I'm not sure about the age, but one is still a baby to young juvenile and my two others are juveniles, both recently developed nuptual pads, one is a bit more mature then the other, in terms of croaking and pads.
The youngest one especially is being really stubborn, the youngest two seem to have made up theyre minds about the poor taste and are refusing like rocks. The slightly older one ate 8 allready in a week, so I have high hopes for him. My adult ones also don't seem to mind the worms.
Could this be an age thing? Since my oldest ones eat nightcrawlers but my youngest are little pigheads.

They were raised on crickets, locusts, silkworms, waxworms, dubias and redrunners and occasional mice.
Edit: Exactly, I use waxworms as treats and attempted the pull the switcharoo, but it din'd fly. These frogs are smart.