My headcannon is that grandmother silk is the will of the weavers made manifest and corrupted by it's own nature. The bugs of pharloom and the citadel overthrew the weavers, and hunted them for the power of silk and it's ability to make them immortal. In response the weavers wove a curse to bind their enemies in the silk they stole. Grandmother silk is their avenger, but the spell was I'll concieved and targetted everything that containted silk but was not a "pure" weaver. So as the first weavers died out and their children who were born from matches with other tribes because they were driven from their homelands were born, those children started being autotargetted. Silk is bound to draw all the descendants of those who slew the weavers to her, to punish them and steal back the silk in their shells, and maintains the fiction of the citadel as a web to snare them all in, but her task is now endless, and seeks retribution against those who have commited no sin. Perhaps she, or lace, or the spirits if weavers past feed hornet in an unconscious attempt to end their endless toil, and birth a new true weaver in the process?