46 STRUCTURE OF THE LEPIDOPTEEA 



by several bold brush-like tufts. The chrysalides are also hairy ; 

 and several of the moths themselves are not only thickly clad with 

 shaggy hair, but a bold tuft often tips the abdomen. 



We must not leave these few remarks on the characters of 

 chrysalides without a mention of the brilliant spots of burnished 

 gold that decorate the pupae of certain butterflies. This is the 

 feature that led to the invention of the term chrysalis, which is 

 derived from the Greek word chrysos, meaning gold. For the 

 same reason the term aurelia has been applied to the pupae of 

 Lepidoptera, this being derived from aurum the Latin name for 

 gold. 



Strictly, then, these two terms apply only to the pupae of a 

 certain number of the butterflies ; but the former is now generally 

 used to designate the pupae of all the Lepidoptera, and is even ex- 

 tended to the corresponding stages of insects of other orders. 



If you examine one of these gold- speckled chrysalides, the 

 brilliant metallic lustre seems to belong to the outer surface, just 

 as if certain spots had been tipped with real gold ; but after the 

 butterfly has quitted its case the beautiful golden spots are gone. 

 This proves that the metallic appearanpe is not due to reflection 

 from the outer surface of the ch^salis, but to a reflection from some 

 structure beneath it. This latter is a very thin membrane which 

 lies just under the outer transparent covering of the chrysalis. 



The period during which the Lepidoptera remain in the chry- 

 salis state varies very considerably in different species, and also 

 depends more or less on the temperature. As a rule, when a cater- 

 pillar pupates before the end of the summer, it remains dormant 

 in the pupal condition for only a few weeks ; but, if late in the 

 summer or in the autumn, it remains in this condition throughout 

 the winter, and emerges in the following spring or early summer. 



Both these conditions are illustrated in the life history of the 

 Large White or Cabbage Butterfly an insect with which we have 

 already become acquainted. We get two distinct broods of this 

 butterfly every year, the first appearing in May and the second in 

 August. The eggs of the first brood hatch in about a fortnight, and 

 the larvae are full grown about four weeks later. These then change 

 to chrysalides, from which the perfect insects (the second brood) 

 emerge in a few weeks the period varying slightly with the tern- 

 perature of the season. From the eggs of this second brood we 

 get another invading army of cabbage eaters that change to pupae 

 late in the summer. These remain dormant till the following 



