Coming from NJ I can safely say cicadeads are not made up.
I promise I am not trying to be an asshole here - is there some joke I'm missing about both of your spelling of cicadas?
In southeastern seaboard US states, some folks called them cicadas, some called them katydids, and some got the syllables confused and said things like katydeads or similar. Some people claimed the name depended on where you’re from.