MACROLEPIDOPTERA 137 



selves by day, and Scoparia the mottled black and white, or grey effects of the lichens 

 which it frequents in all stages. Families, such as the Arctiadae or Zygaenidae, which 

 are generally brightly coloured, do not happen to occur in the islands at all. But after 

 making due allowance for these circumstances, it appears that there is a real local 

 tendency to a dusky suffusion, which often obscures brighter pigments, even when they 

 are perceptibly present. The best evidence of this is furnished by the local forms of 

 apodemic species ; thus the local race of Hypocala andremona is so much overspread 

 with dark suffusion that it has been regarded as a distinct species ; and there is a native 

 race of Heliothis armigera, in which the suffused dark terminal band of the hindwings 

 is considerably extended. Margaroiiia cyanomichla belongs to a group of the genus of 

 which all the other members are sharply and clearly marked with prismatic-white 

 fasciae, but itself has these markings more or less obscurely suffused with dusky-violet. 

 Many species of various genera, when examined with a lens, show a not inconsiderable 

 admixture of crimson, green, yellow, or blue scales, but so combined with other dark 

 scales that there is little or no appearance of these colours in the general effect ; such 

 are Hypenodes cyanias, several species of Eucymatoge, Mestolobes, and even Scopai'ia. 

 It seems to me probable that this tendency is connected with the superabundant 

 moisture of the climate, and is due to influences exerted in the pupal stage, but it is 

 sufficient here to call attention to it as an existing fact. 



Imitative Colouring. 



The question of the assimilation of the colouring of a species to the rocks or plants 

 which it frequents, can only be adequately treated by the collector, who has seen the 

 insect amongst its natural surroundings. But there seem to be two or three cases of 

 apparent mimicry — the assumption by a species of a facies foreign to its own genus but 

 closely resembling that of an unrelated genus — which require to be noticed here, though 

 they can only be adequately explained by observations made on the spot. These are as 

 follows : 



Hypenodes epichaka and H. cyanias (although not at all resembling one another) 

 are so like species of Phlyctaenia in general appearance that at first I had grouped them 

 with that genus, and was much surprised, on a structural examination, to discover their 

 true position. There is no exact imitation, but H. epichaka, which is yellow and black, 

 has a strong general resemblance to Phlyctaenia- chalcophanes, and occurs in the same 

 locality, and at the same season ; and H. cyanias, which is really partially coloured with 

 violet-blue but does not show it to the naked eye, is very similar to P. ennychioides, 

 a dark purplish-fuscous species which is found with it. 



Phlyctaenia heterodoxa is quite unlike all its congeners, and has assumed the facies 

 of Omiodes demaratalis ; the character of the lines and spots has been entirely altered, 



