INTRODUCTION. xv 



bilineolata, Tatosoma agrionata, and Erana graminosa resemble, when at rest, patches 

 of moss ; Selidosema prodii-ctata and 8. lupinata resemble the bark of trees ; 

 Cliloroclystis lichenodes, Declaim floccosa, and Elvia glaucata resemble variously 

 coloured lichens. It is almost unnecessary to point out that all those variations, 

 which tended to conceal the possessors from their enemies, would be preserved in the 

 struggle for existence, and that these numerous and perfect instances of protective 

 resemblance would inevitably result from the operation of natural selection. The 

 dark colouration of Alpine and Arctic Lepidoptera, which enables them to rapidly 

 absorb heat during the short and fitful gleams of sunshine experienced on mountains 

 or in high latitudes, is also an instance of adaptation to conditions through the 

 influence of natural selection. This was first pointed out by Lord Walsingham in 

 1885. The almost complete absence of white species in these localities is a good 

 example of the extinction of forms unfitted to their surroundings. 



CONTRAST COLOURS. In this class of colouring the fore-wings only are protectively 

 coloured, the hind-wings being very conspicuous. Contrast colouring is well exemplified 

 by several of the insects included in the genus Notoreas. The sudden exhibition of the 

 hind-wings during flight dazzles the eye of the pursuer. When the insect immediately 

 afterwards closes its wings and the fore-wings alone are visible, it is extremely difficult to 

 see. This form of protective colouring was also first drawn attention to by Lord 

 AValsingham. (See page 75.) 



WARNING COLOURS. -Insects, which are unfit for food or nauseous, are not protectively 

 coloured, but on the contrary are rendered as conspicuous as possible. This class of 

 colouring is well illustrated by one of our commonest moths, Nyctemera annulata 

 (PI. IV., figs. 1 and 2). The principle of warning colours was first discovered by Mr. 

 A. R. Wallace, and is graphically described in Professor Poulton's entertaining work, 

 ' The Colours of Animals. ' The possession of nauseous qualities would be of little value 

 to an insect, unless it could be at once recognised by insectivorous animals and avoided as 

 food. If a nauseous insect were not easily identified it would speedily be destroyed by 

 what Professor Poulton ingeniously terms " experimental tasting " ; hence, through the 

 process of natural selection, all nauseous species have become very conspicuously coloured. 

 It may be remarked that warning colours are extremely rare amongst the New Zealand 

 species, and I am not aware of any other example than that already given. 



MIMICRY. This term is applied to those remarkable cases where a harmless or edible 

 species imitates in form and colouring a highly armed or nauseous species. No instances 

 of this extremely interesting class of protection are yet known amongst the New Zealand 

 Lepidoptera, but a very perfect example of mimicry exists between two common intro- 

 duced species of Hymenoptera and Diptera, the well-known honey-bee and the drone-fly. 

 The superficial resemblance between these two insects is very close. The bee, as 

 every one knows, is armed with a powerful sting, whilst the drone-fly is unarmed. 

 In this case it can be seen that if a harmless insect varied in the direction of 

 resembling a formidable or objectionable species it would be a decided advantage to it, 

 and such varieties would tend to be continually preserved and improved, through the 

 operation of natural selection. The subject of mimicry has been alluded to here as it is 

 not impossible that some instances of it may yet be discovered in connection with our 

 native 



