Perforated paper is a perforated sheet of paper, usually yellowish in color, which was used on the silkworm farm frames, as a base on which to place the silkworms. Perforated paper could have five types of holes, which corresponded to the five larval stages of the silkworm: the paper was placed on top of the silkworms in the morning and sprinkled with mulberry leaves, so that the silkworms were attracted and passed to the upper level, thus allowing the cleaning and removal of the paper. This was then emptied of excrement and the remains of the mulberry leaves, washed, disinfected, so that it could be reused, even for several years.
Perforated paper was also used to select healthy silkworms, separating them from the weak or sickly ones, which, unable to climb back to the new bed, remained behind and were therefore discarded.
In Mendrisiotto, the paper was blessed in the belief that this would ensure that the silkworm farms were not infested by diseases.