THE YOUNG NATURALIST. 



The colouring is liable to extreme variation, individuals of the 

 same species being anything but constant in their markings. Nature 

 has lavished her choicest favours upon some, and particularly many 

 exotics, while others are more soberly clad, nor is the colouring of the 

 upperside often re-produced upon the upper surface, others again bear 

 a most startling resemblance to withered leaves when at rest, with 

 midrib and stalk complete. Specimens with transparent patches on 

 the wings, quite denuded of scales, are not at all uncommon ; the 

 Clearwings for example : others are semi-transparent, such as Pvocris 

 statices, Setina irrorella, and Arctia fuliginosa, owing to the covering of 

 scales being thinner. Lipans salicis, contrary to what one would 

 expect from its lovely satiny texture, possesses a meagre sprinkling of 

 scales, but the membrane is covered with minute creases. 



Another curious feature consists in the tail-like appendages to the 

 hind-wings of many exotic species, Tvopea leto and T. mimosa for 

 example ; our own Papilio machaon is well known from this peculiarity. 



Pass we now on to the colouring of the wings, which is found to 

 be entirely due to the scaly coating, for when this is removed by rub- 

 bing, the perfectly colourless membrane is left exposed, and the beauty 

 of the insect is gone for ever. The assistance of the microscope is 

 required to show the immense variation displayed by these scales, 

 both as regards eccentricity of contour and peculiarities of structure. 

 Their number is exceedingly great, in fact beyond accurate conception, 

 though Leuwenhoeck has estimated there to be four hundred thousand 

 of these atoms on the wings of the silkworm moth. They are furnished 

 with a base or peduncle, which is received in a similar cavity in the 

 wing membrane, and their method of arrangement reminds one very 

 much of the slates covering the roof of a house, one row partly over- 

 lying that immediately below it. 



From the fact that damaged scales are frequently met with, it has 

 been- ascertained that they consist of two, but more often of three 



layers of membrane, and it is upon the 

 outer layers that the minute granulations 

 composing the colouring matter of the 

 scale are found. These in the white scale 

 oiDoritis apollo (Fig. 1 1) are very numerous 

 and crowded together, and apparently but 

 fair chambers, thus rendering the passage 

 of transmitted light laboured and un- 

 certain. Hence they appear black in the 

 illuminated field of the microscope. Most 

 FigTTo, of this air can be expelled by oil of cloves, 



