LIFE-CYCLE OF CERTAIN AUSTRALIAN BLOWFLIES. 21 
Observations regarding the Life-Cycle of 
Certain Australian Blowflies. 
By Professor T. Harvey Jounston, M.A., D.Sc., University, 
Adelaide; and G. H. Harpy, Walter and Eliza Hall 
Fellow in Economic Biology, University, Brisbane. 
(Read before Royal Society of Queensland, 30th April, 1923) 
Experiments in breeding blowflies previously carried out 
in the biological laboratory of the University, Brisbane, by 
Johnston and Tiegs, showed variations in regard to the duration 
of different stages in their life-cycle, and in order to coilect 
additional data upon this subject similar flies have now been 
bred in larger numbers than previously. 
Decomposing meat was exposed for a period of from six 
to eight hours on certain selected days during the present 
summer (1922-23), so that flies in the neighbourhood might be 
attracted to the carrion and perhaps oviposit thereon. The 
material was then transferred to an insectarium and completely 
isolated from further infestation. Each day such larve as had 
left the meat to pupate and had buried themselves in the 
sand prepared for them were sifted out with a sieve made of 
mosquito-netting and then transferred to one or more vessels 
containing sand, wherein they were allowed to pass their 
prepupal period. Each day these prepupz were again 
examined, and such as had become pup were sifted out and 
transferred to the laboratory to await their emergence. 
A system of consecutively numbering each batch to larvee 
and pupe as they passed through their stages enabled us to keep 
individual records for every specimen handled. From such 
records the tables published in this paper have been compiled. 
Before starting these experiments various observations 
were made to ascertain whether the handling of prepupz or 
pup in the above manner interfered with the various periods 
to any appreciable extent, but we could find no evidence for 
considering that it did. The conditions producing alterations 
in such periods as the season advanced were apparently climatic 
changes. 
