Based on Zoroliebers headcannon, Zoro currently is Luffy lvl, or above him, or Oden lvl, or above him, or he is going to kill Kaido, etc. It's not pretty clear, you can't definite it as it is some imaginary stuff.
So the beetle guy is a random for those kind of characters = Zoro must have destroyed him with his eye alone.
That's the point.