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in precisely the same way as in the Tipulidse. It is not so easy to 

 see in all its details as in these Diptera, on account of the scales and 

 hairs with which the Lepidoptera are clothed. The following facts 

 may, however, be easily observed, and have doubtless been noticed 

 by most breeders of Lepidoptera. 



When the moth is mature and preparing for emergence, the pupa 

 is observed to elongate, the intersegmental membranes being 

 stretched, usually to their full extent. The pupa may be observed 

 in this condition for a longer or shorter period, varying with the 

 species and with the temperature, but it always indicates that emerg- 

 ence is close at hand. If the pupa be opened early in this stage 

 it is found that the added air is wilhin the imago, since the surface 

 and scales which cover it are bathed with fluid which fills all the 

 space between the insect and the pupa skin. When the moth 

 emerges, although it often ejects more or less urate-laden fluid into 

 the abandoned pupa case, it is seen to be much more bulky than 

 the mature moth. This increased bulk consists partially of fluid, 

 partially of air — air that was secreted by the insect to produce the 

 increase of bulk enabling it to extend the pupa case. When the 

 wings are expanded and dried the abdominal bulk diminishes by 

 the re-absorption of the air, and usually by the expulsion of a further 

 amount of fluid loaded with urates. 



It is in my experience not uncommon to meet with a male moth 

 that one takes at first for a female, on account of the enlarged 

 abdomen. I have several times seen this in Zygaenas, and I show 

 you a specimen of Ennomos ietralunaria, which I succeeded in 

 preserving so expanded. These specimens, by some accident or 

 disorder, instead of absorbing the air, reinforced it to their extreme 

 capacity. In this tetralunaria the cavity practically occupies all the 

 abdomen. This inflation of the Lepidopterous imago at its emergence 

 from the pupa serves several objects, or, I may say, has several different 

 aspects, as assisting the moth to escape from the pupa and complete 

 its transformation to an imago. 



The first and chief of these is certainly to obtain tension within 

 the pupa case to cause its rupture, which occurs, of course, along the 

 provided sutures. The actual escape of the moth takes place by a 

 creeping or vermicular movement, very much the same as that by 

 which the larva frees itself when casting its skin. But at the precise 

 date of rupture no such creeping has in ' fact occurred, though it is 

 very probable that the rupture actually occurs, and is in some degree 

 assisted by them at the time when these vermicular movements 

 begin to take place. 



It may be observed in many obtect pupas, and others, that if an 

 attempt be made to open the pupa before the moth is ready for 

 emergence, there is nearly as much difficulty in fracturing the 

 pupa along the sutures provided for the emergence of the moth as 

 in any other direction. I have noted this very often in obtaining 

 immature wings in which to see the tracheal vessels and their relations 



