xm] COLORATION 253 



Wing-Coloration (Plate I). 



Most Odonata have colourless (hyaline) wings. In a very large 

 number of forms, however, a small deposition of yellowish pigment 

 occurs, known as saffroning. This is most commonly found at 

 the base of the hind-wing, less extensively in the fore-wing. 

 Pantala flavescens and Sympetrum flaveolum are well-known 

 examples of this very common form of colouring. Several species 

 of Anax are "saffroned" towards the middle of the wing. In the 

 females of many species, pale yellow or brownish shading occurs 

 at the tips of the wings, or even all over them. In many instances, 

 the tips of the wings are clouded with dark brown or grey pigment. 



Red, brown or black pigment often overlies the patch of 

 saffroning at the wing-base, or may entirely replace it. In some 

 forms (e.g. Tramea) the basal patch is dark red in the male, brown 

 in the female. In others (e.g. Libellula, Leucorrhinia) it may be 

 quite black. 



Fugitive pigmentation of the wing is fairly common. In many 

 forms, particularly in females, pigment is deposited at meta- 

 morphosis and afterwards lost. In other cases, the pigmentation 

 only sets in with old age. 



Apart from the above instances of slight wing-coloration, 

 there are certain groups of Dragonflies in which all, or nearly all, 

 of the species have a definite colour-pattern on the wings. We 

 shall deal with these under four headings: 



1. The Petaliini. The colour-scheme of the wing in this 

 group (Plate I, fig. 1) is quite unique. It is better developed in 

 females than in males. A series of irregular or rounded spots or 

 patches is arranged along the costal border, each being of a rich 

 transparent brown or ruby red colour, surrounded by black. 

 These spots glow like rich jewels on the wings of the live insect. 



2. The aphantochrome Aeschninae. The coloration of the 

 wings in this group is purely auxiliary to the body- pattern. In its 

 highest development, it forms a broad brownish band along the 

 entire wing, either along the costa or slightly below it. The huge 

 Dragonfly Austrophlebia costalis, with its rich brown body and 

 wing-bands, is quite invisible at a distance of a few feet, when 

 resting on the mid-rib of the frond of a tree-fern. The body looks 



