Thinking about insane Locusts makes me think (lol), Psycho Kantus. Out of all the Locust they seem the most likely to go kinda nutty. Think it's because of their spiritual/mystical elements, just reminds me of self flagellating monks or something. Plus, some spiritual beliefs involve the induction of a hallucinogenic state, by like, licking poison toads, sitting in a sweat lodge or eating hallucinogenic plants. It's used as a way to receive visions and visit "other worlds", so I can imagine Kantus doing something similar, going to far and ending up been driven insane by it all.