I.] APPENDIX. 43 



of sucking blood is given them.' The length of time which 

 intervenes between the emergence from the cocoon and 

 fertilization or the deposition of eggs is not stated. 



Sarcophaga carnaria. The female fly dies ten to twelve 

 hours after the birth of the viviparous larvae ; the time inter- 

 vening between the exit from the cocoon and the birth of the 

 young is not given (Oken, quoting Reaumur, 'Mem. p. s. a I'hist. 

 Insectes,' Paris, 1740-48, IV). 



Musca domestica. In the summer the common house-fly 

 begins to lay eggs eight days after leaving the cocoon : she 

 then lays several times. (See Gleichen, ' Geschichte derge- 

 meinen Stubenfliege,' Nuremberg, 1764.) 



Eristalis tenax. The larva of this large fly lives in liquid 

 manure, and has been described and figured by Reaumur as 

 the rat-tailed larva. I kept a female which had just emerged 

 from the cocoon, from August 30th till October 4th, in a large 

 gauze-covered glass vessel. The insect soon learnt to move 

 freely about in its prison, without attempting to escape ; it flew 

 round in circles, with a characteristic buzzing sound, and 

 obtained abundant nourishment from a solution of sugar, pro- 

 vided for it. From September 12th it ceased to fly about, 

 except when frightened, when it would fly a little way off. 

 I thought that it was about to die, but matters took an unex- 

 pected turn, and on the 26th of September it laid a large packet 

 of eggs, and again on the 29th of the same month another 

 packet of similar size. The flight of the animal had been pro- 

 bably impeded by the weight of the mass of ripe eggs in its 

 body. The deposition of eggs was probably considerably 

 retarded in this case, because fertilization had not taken place. 

 The fly died on the 4th of October, having thus lived for thirty- 

 five days. Unfortunately, I have been unable to make an}^ 

 experiments as to the duration of life in the female when males 

 are also present. 



VI. Lepidoptera. 

 I am especially indebted to Mr. W. H. Edwards \ of Coal- 

 burgh, W. Virginia, and to Dr. Speyer, of Rhoden, for valuable 

 letters relating to this order. 



^ Mr. Edwards has meanwhile published these communications in 

 full ; cf. ' On the length of life of Butterflies/ Canadian Entomologist, 

 1881, p. 205. 



