Funny, I was just reading the other thread from last year where some folks got pwned bad sticking to a belief that this happens.
Here's why this myth has spread.
A sick gecko that was kept under temperature had one coming out of it once, but it was from it's cloaca.See, the gecko was too cold to digest the worm, so, with it partially protruding from it's cloaca , it was believed that the worm had eaten it's way out.
And any fish big enough to eat them will make short work of them with their pharyngeal teeth anyway.
And then there's stomach acid, even so, it wont happen.
The mandibles on these beetle larva aren't even close to capable enough, but as creepy as they look it adds to the myth.
No harm in this, though they are high in fat so make them just an occasional treat.
Hope that helps some.