The House Fly 
5 
investigations have proved that the larvae 
or maggots moult twice, showing that there 
are three distinct larval stages (the term 
moult means here the casting of the skin, 
a phenomenon peculiar to insects in the 
larval stage), so that we thus arrive at a 
rough house fly time table. 
Egg from deposition J of a day, say . . 8 hrs. 
Hatching of larva to the first moult . . 1 day 
From first to second moult . . . . 1 day 
Second moult to pupation . . . . . . 3 days 
Pupation to issuing of adult fly . . . . 5 days 
Total life round approximately . . . . 10 days 
Now we see that there is time during an 
average summer for many generations to 
see light. Probably during the summer of 
1911 quite twelve or fourteen. Is it any 
wonder with this enormous power of 
reproduction that this was known as a 
summer of flies ? 
Take the number of eggs laid by a single 
female house fly as averaging 120. There 
may be four such batches from one female, 
so that the huge numbers in which flies are 
found may be easily accounted for — 200 
puparia have been found in one single 
cubic inch of manure ! It will not be a 
