564 SIDNEY I. KORNHAUSER 
present during the fifth nymphal instar is there a decided in- 
crease in length of the pronotum. The effect cannot be pro- 
duced by mechanical means, because the parasites are present 
in the abdomen, whereas the pronotum is attached to the pro- 
thorax alone and receives its material for growth through the 
haemolymph coming into it through the prothorax. The in- 
crease in the size of the pronota in parasitized males is of still 
greater interest when we see that in the parasitized females 
there is no increase, but rather a decrease of about 2 per cent in 
both length and breadth. We are, therefore, led to the con- 
clusion that the 6 per cent increase in size in the males infected 
with parasites is a partial assumption of a female characteristic. 
TABLE 2 
NUMBER OF| AVERAGE 
INDIVID- LENGTH OF 
UALS FOREWING 
mm. 
INiorinallbmalese te eek sit eee eh ae Patan, Sepa he at eat nt ee 25 8.13 
Parasitized males showing medium or complete change to 
female: colonatlone sais. cote ee eee On oe oe 25 9.09 
Parasitized males with male coloration still predominating... 15 8.39 
INormialltfemialesemare tthe sCre ieias iret aan iene Mie as arcana ee 2a 9.78 
Parasitized females with decidedly reduced ovipositors..... | 25 9.81 
Corresponding changes in size and color hold also for many 
other parts of parasitized male Thelia. The length of the fore 
wing was next examined. Measurements were made by remov- 
ing the wings, laying them on a scale divided into tenths of 
millimeters and taking the reading under magnification. The 
length from the posterior tip to the anterior end of the tegula 
was used as the basis of comparison. The averages are given in 
table 2 and a typical example shown in figure 19. 
The fore wing of normal females is on the average 20 per cent 
longer than that of normal males. Parasitized males with 
changed color show an increase of 12 per cent in length over 
normal males. Parasitized males with but slight change in 
color have wings only 3 per cent longer than normal males. In 
the case of the females, the parasites cause almost no change, 
those measured showing an increase of three-tenths of 1 per cent 
