The Thickness of Some Insect Epicuticular Wax Layers

The average thickness of the epicuticular wax layers on the wing membranes and elytra of a number of different insects has been measured by relating the volume of extracted wax to the area of cuticle over which it was spread.

The true surface area of the epicuticle was measured by krypton adsorption.

The ratio of absorption area to apparent projected area was found to be 1·6 for the wing membranes, and 6·7–8·2 for the elytra, with an average value of 4·1.

The wax layers were found to be remarkably similar in thickness on the wing membranes, ranging from 0·11 to 0·13 μ but to vary from 0·11 to 1 ·26 μ in the case of elytra, where the wax thickness appears to be related to extent of modification.