64 



are rarely injured by this leaf -inhabiting form of the insect. The number of eggs in a 

 single gall will vary from fifty to four or five hundred, according to the size of it ; there 

 are several generations of the lice dur- 

 ing the season, and they continue to 

 extend the sphere of their operations 

 during the greater part of the summer. 

 Late in the season, as the leaves become 

 less succulent, the lice seek other quar- 

 ters and many of them find their way 

 to the roots of the vines, and there 

 establish themselves on the smaller 

 rootlets. By the end of September, the 

 g;alls are usually deserted. In figure 74 

 we have this type of the insect illus- 

 trated ; a shows a front view of the 

 young louse, and b a back view of 

 the same \ c the egg, d a section of one 

 of the galls, e a swollen tendril ; /, g, h, 

 mature egg-bearing gall lice, lateral, dor- 

 sal, and ventral views ; z', antenna, and 

 j the two-jointed tarsus. 



When on the roots, the lice subsist also by suction, and their punctures result in 

 abnormal swellings on the young rootlets, as shown at a in figure 77. These eventually 

 decay, and this decay is not confined to the swollen portions, but involves the adjacent 

 tissue, and thus the insects are induced to betake themselves to fresh portions of the living- 

 roots, until at last the larger ones become involved, and they, too, literally waste away. 



In figure 77 we have the root-inhabiting type, Radicicola, illustrated : a, roots 



showing swellings; 6, young louse as it appears 



when hibernating 



of Clinton vine, 



c, d, antenna and leg of same ; e, /, g, represent the more mature lice. It is also further 

 illustrated in fig. 78, where a shows a healthy root, b one on which the lice are working, 

 c root which is decaying and has been deserted by them ; d d d indicates how the lice 



are found on the larger roots ; e, female 

 pupa, seen from above ; /, the same from 

 below ; g, winged female, dorsal view ; 

 h, the same, ventral view ; i, the antenna 

 of the winged insect ; j, wingless female 

 laying eggs on the roots, while k indi- 

 cates how the punctures of the lice cause 

 the larger roots to rot. Most of these 

 figures are highly magnified ; the short 

 lines or dots at the side showing the 

 natural size. 



During the first year of the insect's 

 presence the outward manifestations of 

 the disease are very slight, although the 

 fibrous roots may at this time be covered 

 with the little swellings ; but if the at- 



tack is severe, the second year the leaves 

 assume a sickly yellowish cast, and the 

 usual vigorous yearly growth of cane is 

 much reduced. This is not to be wondered at when we consider the immense number of 

 tiny mouths which are busily at work in all directions sucking the sap and thus depriving 

 the leaves of their only means of subsistence. After a time the vine becomes more 

 ^debilitated and eventually dies, but before this takes place, the lice, having little or no 

 healthy tissues to work on, cannot find sufficient sap for their sustenance, hence they leave 

 the dying vine and seek for food elsewhere — either wandering about under the ground 

 among the interlacing roots of adjacent vines, or crawling over the surface in search of more 



