THE NOCTU.^. 471 



end of September. It then descends the tree, and beneath it 

 spins for itself a slight cocoon, which is generally screened from 

 observation by having a fallen leaf fastened to its upper 

 surface. In this exposed situation it changes into a pupa, and 

 there lies until the following June, when it assumes the perfect 

 form. The insect is, and yet is not, a common one. Those 

 entomologists who have not yet learned to look behind the 

 scenes of Nature's theatre reckon the Iron Prominent to be 

 quite a rarity ; while those who have been long accustomed to 

 the practical study of insects and their ways, experience no 

 great difficulty in obtaining either the moth, the pupa, or the 

 caterpillar, and in consequence consider the Iron Prominent as 

 rather a plentiful insect. 



We now come to one of the largest groups of British Moths, 

 the NocTU^, so called because, as a rule, they are exclusively 

 night-fliers, and never, except by accident, appear in the day- 

 time. In tliese Moths the body is almost always stout and 

 tliick, as is the t'horax, the hairs of which often rise nearly 

 erect, so as to form a sort of crest. Grenerally these Moths hide 

 themselves by day, taking advantage of crevices in walls, the 

 bark of trees, old posts, palings, and invariably selecting those 

 which best harmonise with the colour of their closed wings. 

 So close is often the resemblance between the colour of the 

 insect and that of the object on which it rests, that even the 

 most experienced and keenest entomologists often find them- 

 selves deceived, and have only detected the well-disguised 

 insect when, by an accidental touch, they have forced it to take 

 flight. Even those species which have their imder wings 

 adorned with beautiful colours, have almost invariably tiieir 

 upper wings plainly mottled with brown, grey, black, and dun, 

 so that when they are at rest the splendid under wings are 

 concealed, and their glories veiled by the sombrely tinted 

 upper pair. Many, in fact, most of them, have both pairs of 

 wings coloured in the simplest and least imposing manner, not 

 even having any bold black, white, or brown markings on 

 either pair of wings. Consequently, when a number of Noctua3, 

 which are of about the same size, are collected, it is a very 

 difficult matter to refer them to their proper positions, and 



