i've been sewing and starching for 48 years- i have never had a 'bug problem' but i use, move my fabrics around regularly- i don't know if that has anything to do with it- but it's never been a problem for me- it could be a 'location' issue -- more apt to happen if you live somewhere where bug infestations are a common problem- or if the fabrics are stacked up & left (unchecked) for a long long time-
i've had boxes of fabrics out in my garage for a year- and still---no bugs.