Isn’t that usually referred to with some variation of hystérie?

I would say “des admiratrices en liesse”

While Fred’s answer is nice, I would suggest des groupies en liesse which is less formal and emphasis on the fangirls in concerts.

I think that “Hystérie” is more convenient than “en liesse” which means high joy but without madness.
Yellow was the color of jester and insanes.

Close to that, i should say :
“un public en délire” or “des groupies en délire” if restricted to women.