METAZOA INSECTA. 429 



vine. We will therefore begin with the root-inhabiting 

 type or, as it is called, the Radicicola. This type pro- 

 duces two forms, the sexually mature winged form and 

 the parthenogenetic or wingless form. Since the sexually 

 mature form is nearer the ancestral type than the reduced 

 parthenogenetic form, we will consider it first* Its larva 

 (PI. 1069, fig. i) has distinct tubercles; it develops 

 into the pupa (fig. 2, dorsal view; fig. 3, ventral view), 

 which crawls to the surface of the ground and in sum- 

 mer transforms into the winged insect (fig. 4, dorsal 

 view; fig. 5, ventral view). These winged forms are 

 mostly females. Among them is a smaller, shorter form 

 (fig. 6) which may be the male, although this is not proved. 

 The winged females lay from two to five eggs above 

 ground and die on the approach of winter. Their eggs 

 live through the winter and in the spring the larvae climb 

 to the leaves of the vine and there make galls. Since, 

 however, most of the galls are made by the second or 

 parthenogenetic form of the Radicicola, w r e will describe 

 it next. Its larva (fig. 7) which is at first without tuber- 

 cles, develops them later, as seen in fig. 8, dorsal view ; 

 fig. 9, side view. This form, however, never acquires 

 wings and as it grows it becomes more specialized by 

 reduction ; it hibernates in the larval state, but when the 

 sap starts in the spring, it matures and lays parthenoge- 

 netic eggs which develop into wingless females. It is 

 chiefly these females that give rise to the gall-inhabiting 

 type or the Gallaecola. They make their way out of the 

 earth and to the leaves of the vine which they pierce on 

 the lower side, thereby causing the formation of abnormal 

 growths or galls. The eggs are laid in these galls. They 

 hatch into plump, six-legged larvae (fig. 10, dorsal view; 

 fig. n, ventral view) which leave the gall and find their 

 way to the leaves of the vine. These they in their turn 

 pierce and the resultant gall becomes the home of the 

 adult (fig. 12, dorsal view; fig. 13, ventral view; fig. 14, 

 side view). In this situation the antennae and legs 



