The epidermis (hypodermis) is the single layer of living cells beneath the cuticle that secretes all layers of the exoskeleton. The cuticle itself has three layers (from outer to inner): epicuticle (thin, waxy, waterproof), exocuticle (sclerotised/hardened), and endocuticle (flexible, inner). All cuticle layers are non-living secretions of the epidermis. After moulting, the epidermis secretes a new cuticle to replace the shed one.