Epicuticle of Arthropods

Abstract

THE outermost layer of the integument of insects is a complex structure known as the ‘epicuticle’, composed of several discrete layers the presence of which has been deduced by studying the permeability and deposition of the cuticle¹. Homologous epicuticles have also been investigated in isopod and decapod Crustacea, and in ticks. Although earlier authors described an epicuticle in Myriapoda from staining reactions alone, such a structure has, in fact, not been satisfactorily demonstrated. The sclerotized layer containing phenolic substances in Tachypodoiulus, to which Hackman, Pryor and Todd refer², is almost certainly exocuticle. The absence of a wax layer in the cuticle of millipedes has recently been demonstrated in Glomeris³, and in Paradesmus (unpublished), and it has been claimed that there is no epicuticle in the spider Tegenaria⁴.