Morphological investigations on the wing scales of four species of common Indian butterflies

Abstract

Wing scales of butterflies exhibit extreme diversity in shape, size, colour, and number of spines. They are sub microscopic with a length of 300 to 600µm and a breadth of 150 to 400µm. A typical scale possessed a flat body with basal pedicel and apical crown which is provided with a varying number of pointed edges called spines. Investigations were carried outon the morphology of wing scales in four species of common butterflies viz., Pachilopta hector (Linnaeus 1758), Troides minos (Cramer 1779), Jamides celeno (Cramer1775) and  Eurema andersonii (Linnaeus 1758). Wings of  P. hector possessed nine types of scales, the crown of all are with pointed spines of varying numbers, ranging from one to five. The southern birdwing T. minos, possessed nine types of scales. A major portion of wings with black colour is due to black coloured scales but white bands of the forewings are due to transparent and colourless scales. The prominent yellow colour on the hind wings of this butterfly is due to the presence of a single type of scale with a round crown that is devoid of spines and is fully packed with yellow pigment. Jamides celeno possessed twenty different types of scales, most of them are devoid of spines and the ridges within the scales are not clear. Scales on the upper surface of the wing with ashy blue colour and scales of white bands on the lower surface of the wings are identical and are transparent and colourless. The common grass yellow E. andersonii possessed twentyfive different types of scales, of which thirteen are on the black margins of wings and twelve are in the yellow portions of wings. Almost half of the total number of scales in the yellow portions of the wing is transparent and colourless and in coloured scales distribution of pigment is not uniform.This is the first report on the different types of wings scales in the selected butterflies.