  We report on the measurement of mechanical properties of the transparent
wings of an insect (popularly known as the 'rain fly') using an atomic force
microscope (AFM) down to nanometer length scales. We observe that the
frictional and adhesion properties on the surface of the wings are modulated in
a semi-periodic fashion. From simultaneous measurement of AFM topography it is
observed that the modulation of mechanical properties is correlated with the
modulation of topography. Furthermore, the regions of higher friction are
decorated with finer nanostructures with definite shape. From optical
diffraction experiments we show that the observed modulation and its
semi-periodic nature are distributed over the entire surface of the wing.

Biological Physics;Other Condensed Matter