92 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 



During November 1919 in Brisbane the combined egg and 

 larval stages required from 5 to 7 days (generally 6), and the 

 pupa from 8 to 10 (generally 9) days for development, so 

 that the total period from egg deposition to adult emergence 

 was from 14 to 16 days. This month was dry. During the 

 succeeding January and February (1920) the periods were — 

 Egg plus larval, 4 to 6 days ; pupal, 4 to 8 ; the period between 

 oviposition and emergence ranging from 8 to 12 days during 

 these hot, moist months. 



From later observations made by us in Brisbane (1920, 

 1921), it was ascertained that the housefly could pass through 

 its stages from the egg to the imago in from 7 to 8 days during 

 midsummer, but needed from 11 to 15 during autumn (April 

 and May), and 12 to 16 during winter. Horse-manure was 

 used as the pabulum in all our breeding work with houseflies. 

 Copulation took place in from 4 to 8 days after emergence and 

 oviposition occurred 4 days later. 



Wilhs (1913), working in Sydney during November and 

 December 1910, gave his minimal observation in the case of 

 material incubated at 28-30° C. (82-86° F.), when a period 

 of 12 days elapsed between the date when eggs were first 

 seen and adults first emerged, while with a temperature main- 

 tained at 30-34° C. (86°-93°F.) it was not quite 10 days. 

 He noted that pairing seemed to occur two days after emer- 

 gence, and reported that oviposition took place six days after 

 emergence, at the higher temperatures mentioned. 



Hill (1918) reported that in Melbourne eggs hatched in from 

 12 to 24 hours, flies emerging during midsummer in about 14 

 days after eggs had been laid. Such flies mated in from 4 to 

 6 days after emergence and oviposition occurred about 4 days 

 later. Midsummer in the Southern States of Australia is 

 comparatively dry whereas in Brisbane it is normally moist 

 (January to March). 



Patton and Cragg (1913) reported that, in India, house- 

 flies emerged about the 6th or 7th day after the eggs were laid ; 

 while Smith (1907) recorded that a period of 8 days elapsed 

 when flies were bred from horse-manure at Benares, India. 

 These abbreviated periods are comparable with those above 

 recorded by us as observed during the moist midsummer of 

 S. E. Queensland. 



Hewitt (1914, p. 109) reported that the shortest periods 



