The skin scale itself is made of tough fibres (keratin) that can be difficult for the mite to digest. We known this because researchers found remnants of partially digested skin scales in mite droppings. Perhaps, the skin scales acts as an eatable plate full of food for the mite.
The perfect environment to ripen a discarded skin scale must be warm, damp, dark and still for the fungi, yeasts, bacteria and microorganisms to grow. That environment can often be found in beds and bedding, or anywhere that long periods of time is spent resting, such as relaxing on sofas, or comfortable chairs.
The House Dust Mite and Skin Scales
Photograph by the late Dr Harry Morrow Brown and gifted to housedustmite.com
'Dust Mites', Matthew J. Colloff 2009, CSIRO PUBLISHING, ISBN 978-0-6430-6589-5.