94 PROCEEDINGS OF THE ROYAI. SOCIETY OF QUEENSLAND. 



varied from 2| to 23 days, from 3 to 5 days being required 

 when the temperature was in the vicinity of 80° F. (which 

 corresponds with Brisbane summer). 



Howard (1912) reported that in Washington D.C., during 

 midsummer, larval Kfe occupied 5 days (24 hours -\- 24 hours + 

 72 hours) and the pupal normally 5 days ; while Pierce (1921, 

 p. 129) gave them as 4 and 3 to 10 respectively (U.S.A.). 



Herms (1915) pubhshed maximum and minimum periods 

 for egg, larval, and pupal stages as well as for total periods 

 from egg to imago, based on observations in Berkeley, Cali- 

 fornia. In regard to the last-named period he found it to 

 vary from 12 to 18 days, usually from 14 to 18, but at a tempera- 

 ture maintained at 30° C. the minimum observed was 9| days. 

 The average, minimum, and maximum lengths of time in days 

 required between egg deposition and emergence at certain 

 temperatures were found to be respectively as follows : — ^At 

 16° C— 44-8, 40-5, 48-6 ; at 18° C— 26-7, 23-1, 30-25 ; at 

 20° C— 20-5, 18-8, 22-25; at 25° C— 161, 14-5, 17-8; at 

 30° C— 10-4, 9-3, 11-5. 



Stiles (1921) stated that larvae matured in the shortest 

 time in fermenting materials at a temperature of 90-98° F. 

 (32-2°-36-7° C.) and that at higher temperatures (100-110° F.) 

 they left the hotter portion of the manure in which they were 

 feeding. At temperatures between 65° and 75° F. (18-3-23-9°C.) 

 the " duration of life-round " was 3 weeks, presumably in 

 the vicinity of Washington D.C. 



Hewitt (1914) reported that flies reached sexual maturity 

 in England in August and September in from 10 to 14 days 

 after emergence, oviposition occurring 4 days later. Hutchison 

 (1916) stated that copulation may occur on the first day after 

 emergence, but usually took place between the 3rd and 6th days, 

 provided the temperature was not below 55° F. 



Austen (1920, p. 19) reported that, in June 1915 at Rouen 

 during very hot weather, houseflies bred out in a little more 

 than 6 days from eggs laid in horse-manure, while at Kantara, 

 Suez Canal, in May 1916 during extremely hot weather, about 

 7| days elapsed, but that in England under very favourable 

 circumstances 7 to 8 days were needed. To the latter period 

 there must be added from 14 to 18 days before the emerging 

 flies can lay eggs ; hence in the British Isles during very hot 

 weather about 3 weeks would be sufficient to elapse between 



