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Psyche 
[December 
females show the filled condition. However, 72 of the 79 hosts had at 
least 1 female under the fifth tergite. Thus perhaps only 1 female 
under the fifth tergite fills that location so far as intrasexual competi¬ 
tive effect is concerned. 
Parasite position with only male Xenos pallidus in the host: 
Table 4 shows that the position of male parasites significantly 
changes as the number of parasites changes (p<0.02). Most of the 
male pallidus present alone in a host prefer a location under the 
fourth tergite. Only 7 of the males were in the second segment, and 
only 6 in the fifth segment. Nine of the 14 males located under 
sternites were under sternite 4. The proportion of those under sternite 
4 increases as the number of males per host increases. When 2 males 
are present in a wasp, one goes to the fourth tergite and the other to 
the third tergite. With 3 to 8 males present in a host the preferred 
location is the third tergite. Thus the males exhibit the same pattern 
of intrasexual competition as the females. The losing males are 
shifted from the preferred tergite 4 to the next anterior tergite and 
then to sternite 4. As in the females, only 1 parasite seemed to fill the 
preferred position, since only 1 of the 1.8 hosts with 2 or more males 
had 2 males under the fourth tergite, but 14 of the 18 had at least one 
male there. 
Position of male relative to female Xenos pallidus in the host: 
Clearly the male pallidus tends to extrude from the host more 
anteriorly than the female. This tendency is probably related to the 
fact that males are shorter than females. Ten adult females had a 
head-thorax length of about 1.5mm, an abdomen length of 6-7mm. 
Three of the females contained larvae. The 3 male pupae retaining 
puparium caps had a head-thorax length of 2mm, an abdomen length 
of 2.5-3mm. Comparing the total length of the Xenos to the abdomen 
of the host, it appears that both sexes of parasites usually brace 
themselves near the base of the second abdominal segment of the host 
to extrude the cephalothorax. 
Position of Xenos pallidus in the host when the number of each sex is 
equal: 
Not enough data were available to test the position of females in 
this category. The males did not show a significant change of position 
in the host as number of parasites per host increased (p>0.05). 
However, the trends seemed to be for the males to prefer segment 3 
