44 THE DURATION OF LIFE. [I. 



The latter writes, speaking of the duration of life in imagos 

 generally : — ' It is, to my mind, improbable that any butterfly 

 can live as an imago for a twelvemonth. Specimens which 

 have lived through the winter are only rarely seen in August, 

 even when the summer is late. A worn specimen of Vanessa 

 cardiii has, for instance, been found at this time' (' Entomolog. 

 Nachrichten,' 1881, p. 146). 



In answer to my question as to whether the fact that certain 

 Lepidoptcra take no solid or liquid food, and are, in fact, without 

 a functional mouth, may be considered as evidence for an 

 adaptation of the length of life to the rapid deposition of eggs. 

 Dr. Speyer replies : — * The wingless females of the Psychidae 

 do not seem to possess a mouth, at any rate I cannot find one 

 in Psyche unicolor (graminella). They do not leave the case 

 during life, and certainly do not drink water. The same is true 

 of the wingless female of Heterogynis, and of Orgyi'a en'cae, and 

 probably of all the females of the genus Orgyia ; and as far as 

 I can judge from cabinet specimens, it is probably true of the 

 males of Heterogynis and Psyche. I have never seen the day- 

 flying Satnrmdae, Boiubycidae, and other Lepidoptera with a 

 rudimentary proboscis, settle in damp places, or suck any moist 

 substance, and I doubt if they would ever do this. The sucking 

 apparatus is probably deficient.' 



In answer to my question as to whether the males of any 

 species of butterfly or moth are known to pass a life of different 

 length from that of the female. Dr. Speyer stated that he knew 

 of no observations on this point. 



The following are the only instances of well-established 

 direct observations upon single individuals, in my posses- 

 sion^ : — 



Pi'en's }iapi, var. bryoniae ^ and $ , captured on the wing : 

 lived in confinement ten days, and were then killed. 



Vanessa pro rsa lived at most ten days in confinement. 



Vanessa uriicae lived ten to thirteen days in confinement. 



Papilio ajax. According to a letter from Mr. W. 1 1. Edwards, 

 the female, when she leaves the pupa, contains unripe eggs in 

 her body, and lives for about six weeks— calculating from the 

 first appearance of this butterfly to the disappearance of the 



' Wlien no authority is given, the observations are my own. 



