THE IMAGO. O 



■of the abdomen. In the Limacodidce the abdominal segments are 

 all free, and the cocoon is provided with an easily movable lid. 

 In Adela and its allies the pupa is furnished with a beak, which the 

 moth uses to emerge from its cocoon which is formed of a valvcd 

 larval case. In these lower forms the cremaster or silken girdle 

 round the pupa is rare, and it seems to be used to restrain the 

 effete pupal case when far enough through the cocoon, which is 

 effected in most cases by the elastic cocoon firmly holding the pupal 

 skin. 



{2) The Obtectoe, comprising all the higher forms, with the 5th 

 and 6th abdominal segments free and the moth emerging from the 

 cocoon, leaving the pupal skin retained within it by the cremaster ; 

 the only intermediate case between the two groups Avhich is known 

 being Epermenia, which, though it has an incomplete pupa, leaves 

 it within the cocoon on dehiscence. 



Among the Obtectai there are many devices for breaking through 

 the cocoon, such as specially constructed weak places in the cocoon ; 

 a softening fluid applied by the mouth assisted by special appliances, 

 such as the corneous frontal process of some Pj/rcd'uht' and Noctidda', 

 etc., the spines at end of fore tibia) of many Noctuida', the shoulder- 

 spines of Attacus, etc. In the Pajnliones, which have dispensed 

 entirely with the cocoon, certain genera in each family have lost 

 the power of movement in one or both segments of the abdomen 

 that are free in the rest of the Obtecke ; and the number and position 

 of the free segments in the different groups of Lepidoptera seem to 

 be simply correlated with the problem of most effective levei-age for 

 the various methods of emergence from the cocoon, the power of 

 movement, however, in any segment being never reacquired when 

 once lost. 



The Imago. 



The imago or perfect insect emerges from the cocoon with its 

 wings in a dwarfed and crumpled condition ; they, however, rapidly 

 expand and dry, the muscles being usually stimulated by vibration 

 in the air, probably as a help to the circulation and oxygenisation 

 of the blood-plasma. 



A Lepidopterous insect consists of (1) the head, (2) the thorax, 

 and (3) the abdomen. The head consists of three pieces : the 

 occiput, lying behind the ocelli ; the epicranium behind the antennse, 

 bearing the ocelli or simple eyes, which, however, are often absent, 

 and the large compound eyes made up of a large number of simple 

 lenses ; thirdly the clypeus or frons, occupying the whole front of 

 the head, with the triangular mandibulate areas at each side. 

 The labrum is very minute and concealed by the clypeus, its lateral 

 processes, called piliger, being visible and a triangular medial part, 

 ■which may, however, be the epipharynx ; the labium is small, 

 short, and triangular ; the mentum nearly obsolete ; the lingua is 

 obsolete, its place being supplied by the maxilla}, which form a long, 

 grooved proboscis. 



In Eriocephala functional toothed mandibles are present, in 



