http://ringofbrodgar.com/wiki/SilkPsy determines the q of the silk, from filament to final product.
The way it works is the q of eggs are determined by the parents, things like the herbalist tables and leaves can cap the quality of the worms, and of the cocoons/moths respectively.
If the container is too small, the eggs will fill the space, and yes, eggs do disappear if you drop them or if there is more produced than the space allows.
Filaments will also disappear.
Also, here are some numbers for you to help you optimize your space:
12 worms + 4 leaves per worm, per cupboard. 4 spaces are leftover
(assuming full nature)
1 worm gives 2 filament
5 worms give 1 thread
50 worms to 1 cloth
200 worms to one robe
10 f to 1 thread
10 thread to 1 cloth
4 cloth to 1 robe
400 filament to one robe
Requirements for one robe per round of production:
13 herbalist tables
17 cupboards for worms, not including breeding storage
Breeding: about 6 pairs per cupboard, about 5 cupboards for breeding to get a robe
Additional breeding space is required for replenishment.
About 25 pairs is required for replenishment.
Hope all this helps, lol.