LIFE HISTORY 
25 
portions of the substance in which they have been feed¬ 
ing and transform in the cooler portions. He sug¬ 
gests the idea that this migration outward may be a 
provision for the more easy emergence of the fly when 
the time should come. In some cases he found that the 
pupal stage lasted through several weeks, but he was 
never successful in keeping pupie through the winter. 
Mr. Newstead found that in stable middens the puparia 
occur chiefly at the sides or at the top of the wall or 
framework of the receptacle where the temperature is 
lowest. He found them in such situations often packed 
together in large masses numbering many hundreds. 
In ash pits he found the same conditions. 
Where the manure is in small piles, or is partly spread 
out, the full-grown larvae almost ready for transforma¬ 
tion are apt to migrate into the loose ground under the 
pile or from the edges of the pile outwards, to trans¬ 
form under nearby rubbish. This habit may have a 
very important practical value, since municipal regu¬ 
lations of individual stable practice in regard to the 
removal of manure should take into consideration that 
such removal at intervals longer than those required 
for the larva to reach full growth may result in the 
leaving of many puparia, except of course in cases 
where especial receptacles for manure are in use. 
Emergence of the Adult 
This has been well described by Doctor Hewitt as 
follows: 
“When about to emerge, the fly pushes off the an- 
