CHAPTER XL 



THE COLOURATION OF INSECTS. 

 (Continued?) 



General Scheme of Colouring. So various are the patterns dis^ 

 play ed upon the wings of butterflies, that amidst the lines, stripes, 

 bars, dots, spots, ocelli, scalloppings, etc., it seems at first hopeless to 

 detect any general underlying principle of decoration ; and this is 

 the opinion that has been, and is still, held by many who have made 

 these insects a special study. Nevertheless, we will try to show 

 that beneath this almost confused complexity lie certain broad 

 principles, or laws, and that these are expressed J>y the statement 

 that decoration is primarily dependent upon structure, dependent 

 upon the laws of emphasis and repetition, and modified by the 

 necessity for protection or distinction. 



To render this subject as plain as possible, British species will be 

 selected, as far as possible, and foreign ones only used when native 

 forms do not suffice. 



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. 



M 



