Archeologists now realize that before moths had human sweaters and woolen jumpers to nibble, they were, in prehistoric times, much bigger, much meaner,carnivorous and blood-thirsty.
Moths grew as big as my house, well, not my house, because I live in a flat, but you know, the average house--one with a nice porch, a garden in the back, a room in the attic to put Cousin Elma, you know, a real house.
So anyway, moths grew so big they could move into such a house and be very comfortable.
But eventually, the climate of earth changed, and dinosaurs all caught an integalactic space flight and left the planet (it IS what happened to them) well the moths ran out of good, red, reptile meat, so they became wool-eaters once man came along and started to make sweaters.
Naturally they reduced greatly in size in order to fit into closets and dresser drawers and all those tiny places we like to keep our 'edibles'.