Transpiration Through the Cuticle of Insects

TLDR

The insect cuticle is an effective barrier to water loss, largely due to the outer epicuticle layer, which is thin, non‑chitinous, and resists chemical penetration. Chemical analysis revealed that the epicuticle contains fatty acids and cholesterol‑like molecules.

Abstract

ABSTRACT The cuticle of most insects is an effective barrier to the evaporation of water. Since the work of Kühnelt (1928,1939) it has been known that this impermeability is a property of the outermost layer. It is usually ascribed to the epicuticle—defined as the layer, of the order of 1 μ in thickness, that is not penetrated by the pore canals, contains no chitin, and resists solution in cold concentrated hydrochloric or sulphuric acids. From chemical tests Kühnelt concluded that the epicuticle contained fatty acids and cholesterol-like bodies. He therefore refers to it as a ‘lipoid cuticula’.virtual shape of the substrate