Butterflies - Introduction
( Originally Published 1917 )
In popular esteem the butterflies among the insects are what the birds are among the higher animals - the most attractive and beautiful members of the great group to which they belong. They are primarily day fliers and are remarkable for the delicacy and beauty of their membranous wings, covered with myriads of tiny scales that overlap one another like the shingles on a house and show an infinite variety of hue through the coloring of the scales and their arrangement upon the translucent membrane running between the wing veins, It is this characteristic structure of the wings that gives to the great order of butterflies and moths its name Lepidoptera, meaning scale-winged.
In the general structure of the body, the butterflies resemble other insects. There are three chief divisions: head, thorax, and abdomen. The head bears the principal sense organs; the thorax, the organs of locomotion; and the abdomen, the organs of reproduction.
By examining a butterfly's head through a lens it is easy to see the principal appendages which it bears. Projecting forward from the middle of the top is a pair of long feelers or antennae. Each of these consists of short joints which general may be divided into three groups : first, a few large joints at the base connecting the feeler with the head; second, many rather small joints which make up the principal length; third, several larger joints which make up the outer part or "club" of the antennae. In the ease of the Skippers, there are in addition a number of small joints coming to a sharp point at the end of the club. Just below the insertion of the antennae on each side of the head are the large compound pound eyes, which are almost hemispherical. With a powerful glass, one can see the honey-comb-like facets, of which there are thousands, making up each eye. Just below the eyes there are two hairy projections, called the palpi, between which is the coiled tongue or sucking tube.
Anatomically the thorax is divided into three parts the prothorax, the mesathorax, and the metathorax; but the lines of division between these parts are not easily seen without denuding the skin of its hairy covering. The prothorax bears the first pair of legs. The mesathorax bears the front pair of wings and the second pair of legs. The metathorax bears the hind pair of wings and the third pair of legs. In many butterflies, the first pair of legs so reduced in size that they are not used in walking.
The abdomen is composed of eight or nine distinct rings or segments, most of which have two spiracles or breathing pores, one on each side. It also bears upon the end of the body the ovipositor of the female or the clasping organs of the male.