1929] 
Stylopized Vespidse 
277 
tion no tendency for the parasites to move back in male 
hosts is apparent. 
The Sex of the Parasite 
The parasites listed above include 245 males and 206 
females, divided as follows: 
Parasites of 
$ 
$ 
Parasites of 
$ 
2 
Masaridinas 
.. 7 
3 
Monobia . . 
. . 3 
8 
Zethinae . . . 
. 3 
3 
Montezumia 
. . 3 
2 
Eumenes . . 
. 6 
12 
Polybiinae . 
. . 10 
13 
Odynerus . . 
. 32 
59 
Polistes . . 
. . 144 
61 
Pachodynerus . 
. 11 
21 
Vespa . . 
. . 5 
8 
Ancistrocerus . 
. 21 
16 
It will be seen that male parasites are known, and in- 
deed are common, in all groups; so that no such condition 
exists in the Vespidse as in the bee genus Halictus where 
hundreds or even thousands of female parasites are found 
for each male. The preponderance of male Xenos in Polistes 
is striking, but except in Odynerus, where an excess of 
female parasites is indicated, the other numbers are too low 
to be worthy of discussion. 
We have compared the sex of the parasites found in 
male and female hosts, but as there is no very significant 
result we do not give the summary in detail. As far as our 
data go, male and female parasites infest male and female 
hosts indiscriminately. 
Number of Parasites per Host 
There is some difficulty in counting the number of para- 
sites per host from published records, as it is not always 
stated definitely whether the host contained one or several 
parasites, or whether the several parasites mentioned came 
from one or more hosts. Our summary, therefore, includes 
only those cases of which we are quite sure, either from a 
personal examination of the specimen, or from a definite 
statement in the record. In the following list we give the 
