Silverfish, really?? I never knew that!! I dont use starch, not even when I iron clothes.
The only time I have ironed seams open was when I made a recycled blue jean quilt top....my LAQ said it would be to bulky in the seams if I ironed to one side.

The new patriotic block swap directions say to iron the seams open. I'm going to be starting on them this weekend...so I'll have to see how that is going to work out.