The body of by far the greater number of species is either darker or of the same tint as the mass of the wings; and only in rare cases lighter. When the body has different tints, it is generally found that the thorax and abdomen differ in colour, and in many cases the base of the thorax is emphasized by a dark or light band.
On the wings the functional importance of the parts attached to the body is generally darker, perhaps never lighter, than the ground of the wing, and is frequently further emphasized by silky hairs. This has already been sufficiently pointed out.
The wing area may be divided into the strong costal margin, the hind margin, the nervules, and the spaces; and, however complex the pattern may be, it is always based upon these structure lines.
In the majority of insects the costal margin is marked with strong colour. This may be noticed in Papilio Machaon, P. merope, Vanessa antiopa, and the whites in [Plate IV]. The extreme tip of the fore-wings is nearly always marked with colour, though this may run into the border pattern. This colour is dark or vividly bright, and we know no butterfly, not even dark ones, that has a light tip to the wings. Sometimes, it is true, the light bead-border spots run to the tip, but these are not cases in point. The development of tips has been traced in [Chapter VI.], and need not be repeated.
The hind margin of both wings is very commonly emphasized by a border, of which V. Antiopa, [Pl. III. Fig. 3], is a very perfect example.
The border pattern may consist of one or more rows of spots, lines, bands, or scallops;[31] and there is frequently a fine fringe, which in many cases is white, with black marks, and to which the term bead-pattern may be applied.
A definite relation subsists in most cases between the shape of the hind margin and the character of the border-pattern. The plain or simple bordered wings have plain border patterns, and the scalloped wings have scalloped borders; or rather scalloped borders are almost exclusively confined to scalloped wings. In our English butterflies, for instance, out of the 62 species:—
33 have plain margins to the wings. In all the border is plain, or wanting.
20 have the fore-wings plain, and the hind-wings scalloped, and in all the hind-wings are scalloped and the fore-wings plain, or with slightly scalloped border-patterns.
9 have scalloped margins and scalloped border-patterns.
Another relation between structure and pattern is found in those insects which have tailed hind-wings, for the tail is very frequently emphasized by a spot, often of a different colour from the rest of the wing as in the Swallow-Tails, Plates [IV.] and [V].