566 SIDNEY I. KORNHAUSER 
over normal females. The wing length in parasitized males 
behaves just as did the size of the pronotum and the degree of 
change is correlated with the change in the color of the pro- 
notum. Pronotum color is the best index one can find for prac- 
tically all the changes in the male. 
A qualitative change in the wing is also seen in parasitized 
males (fig. 19). Whereas in normal males melanic pigment 
extends diagonally through the second apical areole to the base 
of the fourth apical areole, in the female it forms only a spot in 
the second and is restricted to the distal two-thirds of the fourth 
areole. Parasitized males show a distribution of pigment like 
that of normal females. 
Turning to the other thoracic appendages, the legs, we find 
that those of normal females are longer and stouter in every 
segment than those of the male. The size relation in the third 
pair is shown in figure 20. Similar to what was observed in the 
pronota and wings, parasitized males exhibit an increase in the 
size of the legs. This increase is especially noticeable if we 
compare the length of the tibia and tarsus taken together in 
each of the classes shown in figure 20. 
Not only do the thoracic appendages increase in size in para- 
sitized males, but the thorax itself becomes larger. This is best 
measured by comparing the acrotergites of normal males, nor- 
male females, and parasitized individuals. This plate, which 
extends from the metanotum ventrad between the mesothorax 
and metathorax and serves for the attachment of locomotor 
muscles, gives us a good idea of the cross-section of the thorax 
and the relative surface provided for the thoracic musculature. 
A comparison was made of thirty acrotergites removed entire, 
ten from each of the three classes represented in figure 21. Not 
only do parasitized males show a noticeable increase in the size 
of the acrotergite, but even the form of the aperture through 
which the digestive tube passes and the contours of the thick- 
ened ribs of the chitinous plate become female in character. 
The increased acrotergite indicates, I believe, that the muscles 
which move the enlarged appendages have become larger than 
the muscles of normal males. Although dipterous parasites are 
