Fooly Cooly

Could someone PLEASE explain this anime to me? It's not often I can't follow the storyline ... Hell I could even follow Aeon Flux ... But this one escapes me.

Insane girl with a semi-sentient vespa and a chainsaw-like guitar she swings like a hammer
said girl beats a kid over the head with it and he starts developing a cubist horn on his forehead ... said horn becomes two robotic creatures battling ...

WTF?

Hmmm

Why do all the alien insects have mouths that look like angry female crotchs?