Where did the term young grasshopper come from?

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".