380 
Parasites of Common Flies 
fourth day. On dissecting the body 343 eggs were found in the ovaries. Of the 
larvae 80 died, possibly due to infection by the insertion of the ovipositor (see 
Fabre, p. 408). From 170 puparia flies emerged within 25 days and from 193 
there emerged 47 $ and 146 $ A. manducator between the thirtieth and ninety- 
fifth days. The remaining 101 puparia were examined on the hundred and 
seventieth day; 88 contained dead fly remains, 5 dead adult A. manducator 
and 8 dead A. manducator larvae. In this case the female A. manducator de¬ 
posited eggs in at least 206 of the larvae provided. 
Under more natural conditions it is likely that she would have infected a 
greater number as the ovaries contained at least 549 eggs. 
In another experiment a fertilised female A. manducator was given 58 large 
larvae in succession, and was seen to insert its ovipositor into each in turn. 
All these larvae pupated. From five flies emerged on the twenty-fifth day, 
and from 28 of them 10 $ and 18 $ A. manducator between the thirty-fifth and 
ninety-fifth days. The remaining 25 puparia were examined on the hundred 
and seventieth day. Seven contained dead fly remains and 18 dead adults or 
larvae of A. manducator. 
In this case all the parasitic eggs were deposited on the same day in larvae 
of the same age, which were kept under identical conditions, yet the first adult 
A. manducator emerged on the twenty-fifth day and the last on the ninety-fifth 
day. All the 10 S and 4 of the $ emerged between the twenty-fifth and thirty- 
seventh days, and the other 10 $ between the sixty-first and ninety-fifth days. 
In a third experiment a fertilised female A. manducator was placed in a 
glass jar and four large fly larvae introduced. The parasite soon oviposited 
in each larva and after an interval when the larvae began to move about 
attacked each a second time. The experiment was repeated until she had ap¬ 
parently oviposited twice in 19 larvae. Five of these larvae died, and the 
other 14 pupated. From one a fly emerged on the twenty-fifth day. 2 S and 
1$ A. manducator emerged on the thirty-first, forty-second and forty-third days 
and 4 $ between the seventy-first and eighty-fourth days. The six remaining 
puparia were examined on the hundred and seventieth day. Three contained 
dead fly pupae, one a dead A. manducator and two dead A. manducator larvae. 
This experiment shows that flies may sometimes develop from larvae in 
which the parasite has presumably deposited two eggs and that from such 
larvae only single specimens of A. manducator emerge. 
In a fourth experiment an unfertilised female A. manducator was placed in 
a jar with 191 large fly larvae. She was found dead on the fourth day, and on 
dissection only 17 eggs were found in the ovary. 
Of the larvae 76 died and the rest pupated. From these 19 flies emerged 
on or before the twenty-first day. Between the forty-first and forty-seventh 
day 42 $ and between the seventy-second and seventy-ninth 29 $ of A. mandu¬ 
cator emerged. The remaining 25 puparia were examined on the hundred and 
seventieth day. Dead fly remains were found in 13 and dead A. manducator 
in 12. 
