ATTACKING THE ROOTS. 



235 



It is also further illustrated in Fig. 243, where a shows a 

 healthy root, b one on which the lice are working, c a root 

 which is decaying and has been deserted by them ; d, d, d, in- 

 dicate how the lice are found on the larger roots ; e represents 

 the female pupa, seen from above, / the same from below, g 

 winged female, dorsal view, h the same, ventral view, i the 

 antennae of the winged insect, and / the wingless female, lay- 

 ing eggs on the roots ; h indicates how the punctures of the 

 lice cause the larger roots to rot. Most of these figures are 



Fig. 242. 



highly magnified, the short lines or dots at ih^ 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 swell- 

 ings; but, if the attack is severe, the second year the leaves 

 assume a sickly yellowish cast, and the usual vigorous yearly 

 growth of cane is much reduced. In course of time the vine 

 usually dies; but, before this takes place, the lice, having little 

 or no healthy tissue to work on, leave the dying vine and seek 

 for food elsewhere, either wandering under ground among 

 the interlacing roots of adjacent vines, or crawling over the 



