﻿SO 



THE WING SCALES OF THE ORNITHOPTERA. 



In Plates 58 and 59 of this work I give a series of figures of the scales which serve to ornament the wings of some of 

 the species included in the tribe Troides. I do not profess to have drawn all the varieties that might, by careful 

 examination with the microscope, be discovered ; for although the two plates contain an aggregate of 84 figures, very 

 many more might be added. The forms of the Lepidopterous scales are exceedingly numerous in all the groups. 

 Lyonnet, in his posthumous memoirs, filled several quarto plates with representations of the scales found on the wings 

 and body of the European goat moth Cossus Ligniperda, no two of them being precisely alike. It would be impossible 

 to determine the limits of species or genera by the characteristics of these scales, so far at least as the Troides are 

 concerned ; for some of the forms are common to all the genera and species, though others appear to be peculiar to 

 special species. But in these genera which are provided with Androconia there are at least two types: those of 

 Ornithoptera and JEiheoptera in form being quite unlike their analogues in Trogonopiera and Pompeoptera. In the first two 

 genera they consist of a multitude of exceedingly minute scales of 2 or 3 forms situated on the pupas-form <? stigma of 

 the anterior wings (see pi. 58, figs. 36), while in the latter they consist of an immense aggregation of long silky hairs 

 of almost immeasurable tenuity, contained in a fold or pouch of the abdominal margin of the wing. In Schoenbergia 

 and Drurya this character of scale appears to be absent, though I have no doubt some scales or hairs may ultimately 

 be found, which serve a similar purpose in the economy of the insect. 



The general scales are attached to the membranous surface of the wing by the slender stem or peduncle at their base ; 

 in some cases, perhaps in all, this peduncle throws out delicate rootlets, by which the peduncle is probably rendered 

 more secure in its insertion into the minute indent of the membrane. Contrary to the popular idea these scales are 

 generally so firmly fixed in position, that it is by no means an easy task to denude the membrance of even a few scales. 

 This, at any rate, is true of many of the diurnal lepidoptera, though it is often otherwise in some of the Heterocerous 

 Lepidoptera. 



The scales may almost be divided into groups, for some are quite oval, or suboval, others are wedge-shape, leaf- 

 like, petal-shaped, or like fish scales ; often dentate at the apex, with 2 to 7 or even more dental notches — these notches 

 generally varying in length and width in the same scale. Other scales are very narrow and relatively long. They are 

 formed always of two lamellae — sometimes (perhaps ?) of three. But in Troides I cannot satisfy myself of the existence of 

 more than two. They are always granulated or striated on one or both surfaces — sometimes quite from their base ; but 

 often the basal and lateral portions for a short distance are simply transparent, from the absence of striae. On many 

 of the scales there are cross striae ; the striae are generally parallel to each other ; sometimes these are duplicated and 

 run the entire length of the scale ; or they form rows of oval or rounded dots. Their colours vary greatly when micro- 

 scopically examined, even those taken from the black areas of the wing : for some may be blue, violet or green ; and I 

 can find no absolutely black scales— though many were very dark and almost opaque — caused by the closeness and 

 immense number of their granulations and striae. Between the striae are many pigment cells ; but the way the 

 sculpturing of the scales is arranged decides whether they shall give off prismatic colours or not. Some of the scales 

 from golden yellow surfaces are warm green or rosy pink ; and others from green or brown areas are nearly white and 

 very diaphanous. 



Dr. F. Urech, in Zool. Anzeig, vol. 15, pages 305-6 (1892), divides the scales of the Lepidoptera into 5 classes, 

 according to the various phenomena that they exhibit: — -i. Scales only containing chemical colouring matters, and 

 which exhibit no interference colours, found on the wings of the Vanessas and other species. 2. Scales which contain 

 chemical colouring, and also interference colours, found on the wings of the Vanessas and other species. 3. Scales 

 which exhibit interference colours on the wings, and possess also colouring matters which are soluble in water, as in the 

 Lyr-cEnida;. 4. Scales in which the colours are due to an underlying layer, as in the blue and violet scales of some 

 Vanessas. 5. Variously coloured overlying scales which exhibit mixed colours, as in Papilio (and some of the 

 Ornithoptera. 



These 5 classes do not really include those connected with the sexual markings, which are generally found to be scent 

 scales, intended either to attract the other sex or to repell undesirable visitors or foes ; for as Burmeister and E. Haase 

 have shewn, there is what they call a tire-spur (Schienensporn) which is sometimes found on the antennae — a secondary 

 sexual character, intended to aid attraction. In it is a gland which appears to moisten the olfactory organ in the 

 antennas. In specially well developed feelers of the $ , and on the plump wingless females of some of the Geometrae, 

 we are told it is absent, and only occurs in the Heterocera when both sexes are capable of flight. 



