Was a mega-insect discovered in Mammoth Cave, Kentucky? No, that's not true: a video that went viral with that claim actually showed a puppet used in a movie. The caption superimposed on that video is fake.
Holy sh*t, y'all 🦂#kentuckykicksass
Here is an example of the video:
The name and quote from "speleologist" Chaz Winters kind of gives away the fact that the video is a joke:
"First of it's kind. I ain't never seen nothin' like it. That's a big bug, y'all!"
The clip was taken from a behind the scenes look at how the "Rollie Pollie" creatures were made that were seen in the 2013 movie Pacific Rim:
You can see the actual footage that was taken for the fake clip near the end of this video.