what are double and flimsy cocoons

Hi,
Double Cocoon :- A double cocoon is spun by two worms, producing a filament, which does not unwind smoothly and tangles easily. As these cannot be reeled along with normal cocoons, double cocoons are used for manufacture of a coarse, non-uniform, stubby yarn called "doupion". Double cocoons may be caused by crowded mounting conditions, high temperatures, high humidity and mutation of silk species.

Filmsy Coccon :- In this type of cocoons, the shell is loosely spun in layers and has a low silk content. These cocoons are easily overcooked and produce waste.