Endermites Spin around like crazy and can't be killed

This time, I am POSITIVE it is a glitch.

Okay, so, I don't know why there are so many endermen in my world, but they always teleport everywhere and now my world is loaded with endemites.

Changing the difficulty usually doesn't work when this happens, as the endermites are still there for some reason. Restarting the game helps, but then if I change the difficulty it starts all over again...

When Trying to kill them, nothing happens. They just sit there. One was floating and spinning around...

I Did backup my world, but the pre-14w26 world has had this happen to it before, also.

Any Help Will Definitely Be Appreciated. Thanks.

~Fluffer