Where did the term young grasshopper come from?

Answer 1

After someone's grasshopper got old they then referred to its earlier existence as the young grasshopper. It just kind of stuck. Basically any grasshopper that isn't old is a young grasshopper. A middle aged grasshopper probably would not be called a young grasshopper but merely just a "grasshopper".

I never heard of that. Instead it refer's to the Kung Fu TV series where the main character was being taught his Kung Fu skills, as a child, his mentor (with flashbacks in the TV show) would call him YOUNG GRASSHOPPER. You most often heard "Have patience Young Grasshopper".