Manchester Memoirs \ Vul. li. (1906), No. 1. 



Remarks. 



The length of the larval stages of Series 1 was due 

 to the low and variable temperatures experienced 

 during that time. During the pupal state very 

 hot weather supervened (September 1st) which 

 caused the flies to emerge in the shortest time 

 I have observed in the experiments. 

 During the same period of hot weather Series 3 were 

 in the third larval stage which was prolonged by 

 the larvae being allowed to remain in rather dry 

 conditions. Series 4 and 5 were in their first and 

 second larval stages during the few hot days, and 

 both these stages were short. Immediately after 

 the hot weather which we had for a few days at the 

 beginning of September, there was a drop in the 

 temperature and it has been comparatively low 

 since, referring to the mean temperature of course. 

 This low temperature caused an excessive prolonga- 

 tion of the 3rd larval and pupal stages of Series 

 4 and 5. 

 It will be seen from the table that there is considerable 

 difference in the time taken by different batches of larvae 

 to develop. The shortest time is twenty days and the 

 longest thirty. 



If the shortest times of the different stages be taken, 

 it is found that they are : 



Time from deposition of egg to emergence 



of larva ... ... 24 hours. 



First larval stage ... ... ... ... two days. 



Second larval stage... ... ... ... two days. 



Third larval stage ... ... ... ... four days. 



Pupal state ... ... ... ... ..•. six days. 



The whole period from the deposition of the egg to 

 the exclusion of the imago would last about fifteen days, 



