18 
Psyche 
' [February 
The specimens are from various sources, but the great majority 
were reared from puparia obtained under natural conditions, so that 
the general result should show a nearly normal or actual ratio of the 
sexes. 
The table follows. 
Taste IV. Proportion OF THE SEXES IN Nasonia brevicornis. 






. Total. | Ratio. 







ee Source. pate: Males. | Females 
| | | | | 
Tanti hal kar ae IF, 
1 | Principal | Sept. 9—Oct. 20 142 438 580 
| misc. rearings 
during season 
2 Nason Collec-| May 11—Sept.17| I 9 10 
tion 1894-1895 
3. | Phormia regi-| Sept. 29 710 786 | 1496 
| na 
4 | Phormia regi-| Oct. 1895 2808 | 4703 
na 
| 
1 
5 Phormia regi-| Oct. 228 116 344 
na 
6 Various Sept. 41 49 90 
7 Various Sept.—Oct. 64 82 146 
Sums: 3081 4288 | 7369 
Per- on Pe 
me ie 41.81 58.19% 


1:3 

1:9 
Remarks. 
Comprises all ac- 
cessioned rear- 
ings. See pp. 
7-9. 
From sweepings, 
Algonquin, Illi- 
nois. 
1:1+ | From a single host 
21+ 


131+ 

ea 
lot from a de- 
composed  cad- 
aver, city dump- 
ing-grounds. 
Same as lot No. 3, 
later, excluding 
1000 removed at 
random for ex- 
perimental pur- 
poses. 
Host puparia in 
fecal matter, 
miscellaneous. 
Reared. 
From isolated pu- 
paria of Musca, 
Sarcophaga, 
Phormia and 
Chrysomyia. 




The general result shown in the table is about what one would 
expect if consideration is taken of the fact previously pointed out, 
namely, that the species is occasionally parthenogenetic, which, 
however, follows no general law in the Hymenoptera. 
It should be 
explained, in regard to lot No. 4 in the table that, after it was separated 
from lot No. 3, the first 1000 individuals of mixed sexes coming to 

| 

