A contribution to our knowledge of the Stylopidae. 245 
I raised Xenos, all of them females, the faded appearance is especially 
noticeable upon the dorsum of the abdomen. The first abdominal 
segment which is normally piceous with a narrow apical yellow band 
is in this case almost entirely bright ferruginous, or is ferruginous 
with the border yellow. The remainder of the abdomen is normally 
piceous, but the posterior margins of the segments, especially the 
second and third tend to become more or less broadly dull ferruginous 
in stylopized specimens. Possibly the reason that the reddish Polistes 
Fig. A. Stylopized specimens of Polistes annularis. 5 : 4. 
are not affected, is that red is a more primitive color than piceous t), 
and that the color simply becomes arrested at this stage, and does 
not tend to become so before the red stage ?). 
Of the four wasps, three could readily protrude the sting, although 
they were less savage than usual. The fourth was however unable 
to- make even a pretence at stinging. 
The attacks of the parasites are not confined to the female sex, 
but they also occur on male wasps. From this it is probable that 
1) At least in this case. 
2) Dr. Wu. M. WHEELER informs me that he now has in prepara- 
tion a paper containing data upon the nature and extent of the color- 
change in stylopized individuals of Polistes metricus Say. 
