1979 ] 
Dunkle — Xenos pallidus 
329 
moldy, and 3 of the male still in pupal cases had apparently died and 
become moldy. The average number of parasites per infested host 
was 2.1. 
Table 2 compares the number of hosts observed with each parasite 
load to the number expected from a truncated negative binomial 
distribution obtained by modifying the method of Crofton (1971). 
This method predicts the number of hosts for each parasite load by 
referring to the pattern established with small parasite loads, in this 
case the number of hosts observed with 0-3 parasites. Table 2 shows 
an extremely close correspondence between observed and expected 
numbers of hosts until the parasite load reaches 9 and 10 per host. 
Thus 9 or more parasites probably kill the host relatively rapidly. 
Sex ratio of Xenos pallidus: 
The Xenos sex ratio was 423 males to 772 females or 1:1.83. This 
ratio probably results from the more rapid death rate of hosts carry- 
Table 1. Number of male Polistes annularis with each combination of male and 
female Xenos pallidus parasites, collected at Newnan’s Lake, Alachua Co., Florida, 7 
Oct-12 Nov 1979. 
Males 
per 
host 
0 
1 
Females per host 
2 3 4 
5 
6 
Hosts 
0 
10973 
246 
56 
15 
3 
4 
1 
325 
1 
55 
55 
24 
13 
6 
2 
155 
2 
9 
13 
11 
5 
2 
3 
43 
3 
6 
5 
7 
4 
2 
2 
26 
4 
1 
2 
3 
1 
2 
9 
5 
1 
2 
2 
5 
6 
1 
1 
2 
7 
1 
1 
8 
1 
1 
1 
3 
Total 
Hosts 
73 
325 
106 
38 
15 
11 
1 
569 
Table 2. Number of male Polistes annularis observed with 0 to 10 Xenos pallidus 
parasites compared with the number expected from a truncated negative binomial 
distribution, truncated at 3 parasites per host. 
0 
1 
2 
Parasites per host 
3 4 5 6 
7 
8 
9 10 or more 
Observed 
10973 
301 
120 
58 
33 25 
14 
9 
6 
2 1 
Expected 
10972 
302 
118 
60 
34 21 
13 
9 
6 
4 8 
