Every thing I have been reading that mentions silverfish eating starch is talking about paste which is made out of wheat flour not corn flour. The little buggers love wallpaper paste and the paste that holds layers of cardboard together. Also the glue that holds books together and the paper on some types of insulation seem to attract the buggers. I think corn starch might actually act as a dessicant (drying agent like talcum powder) and cause them severe discomfort. They like moisture and cornstarch absorbs moisture.
One article did talk about fabric but it was talking about a different kind of bug that eats rayon and may damage cotton in it's quest for rayon but can't digest cotton.
So, feel free to starch your fabrics but get rid of the ugly wallpaper!