TRACHEATA 367 
=) 
which are provided with the rudiments of wings ; before their 
last change of skin they creep above ground, and then at the 
Fic. 207.—Phylloxera vastatriz, winged female 
which lives on leaves and buds of vine, and 
lays, parthenogenetically, eggs of two kinds, 
one developing into a wingless female, the 
other into a male. After Girard. 
final moult a winged female emerges and flies away. This 
form serves to spread the vine disease from one district to 
Fia. 208. 
a. Phylloxera vastatriz, male 
produced from small egg 
(c) laid by winged female 
(Fig. 207). 
b. Large egg. 
c. Small egg. 
d. Wingless female from large 
egg (6) laid by winged 
female. 
After Girard. 
another. It is also parthenogenetic, but lays two kinds of 
egos. From the larger of these a complete female hatches out, 
whilst the smaller produces in eight to ten days a male. This 
