They’re emperor gum moths, although since those mostly eat eucalyptus I suppose they’re a stand-in for some other emperor. In any case if it’s not just some cunning trick but actually a spell component for summoning eagles, Gandalf really should have been looking into how easy it would be to breed them and carry some with him.
I honestly would forgive it a little more if they had been hawkmoths, just for the name.
