374 
Parasites of Common Flies 
one of these puparia 3 $ and 12 $ emerged. The others were subsequently 
dissected and found to contain dead fly remains. 
In a fourth experiment two females were confined with six puparia on 
May 3, 1917. 4 d and 39 9 emerged on May 28 from three of the puparia. On 
dissecting the remaining puparia one dead male, two dead females and 10 
dead nymphs were found in one, several dead chalcid larvae in another, and 
dead fly remains in the third. 
In a fifth experiment a single female was confined with three puparia on 
May 1. From these puparia 7 $ and 27 9 emerged on the twenty-sixth day. 
In these experiments 40 infected puparia yielded 78 $ and 394 9, a mean 
of 2 d and 10 $ from each puparium; the number emerging from each puparium 
Fig. 16. Muscidifurax raptor Q. X 20. 
being almost the same as from the naturally infected puparia. In this chalcid 
the proportion of males to females is much greater than in M. acasta, and 
the number of eggs deposited in each puparium much less. 
Muscidifurax raptor. 
A few specimens of the chalcid, 3 $ and 12 9, emerged between August 23 
and September 26, 1917, from puparia collected during July of that year. 
Five 9 to which 20 fly puparia were given lived 40 to 50 days. From two of 
the puparia single females emerged, the other 18 containing dry fly remains. 
Necremnus leucarthros Thoms. 
Six examples of this chalcid, 1 $ and 5 9, emerged between August 5 and 
September 3, 1917, from puparia collected earlier in the summer. 
