THE CUTICLE OF THE TWO-SPOTTED SPIDER MITE, TETRANYCHUS TELARIUS (LINNAEUS) (ACARINA: TETRANYCHIDAE)

Abstract

The cuticle of T. telarius (L.) examined by light and electron microscopy and subjected to tests for chitin and lipids is shown to be a thin layer with a pattern of external ridges. It is about 1.25 microns thick measured in the troughs and twice that thickness measured at the ridges. The ridges average from 1 to 1.6 μ apart. There is no tectocuticle but an outside lipoid layer and a dark-staining non-chitinous epicuticular layer from 0.1 to 0.2 μ thick. A double-layered inner procuticle is present. The outer layer of the procuticle remains unstained in contrast to the dark-staining inner layer. The inside surface of the cuticle bears elevations or ridges opposite the external troughs. The epicuticle only is shed at molting. It bears the branched setae and over the eyes is striated, the ridges being about 0.14 microns apart. Either one or both layers of the procuticle contain chitin.