228 



FESTS OF ORCHARD AND SMALL FRUITS 



same species of lice cause swellings which later decay, resulting in the 

 death of the roots. The serious injury is that done by the root-in- 

 habiting forms. 



On native grapes, in the eastern states, this 

 insect is fairly common, but the roots of these 

 grapes are resistant and no notable damage 

 results. On imported grapes in the Pacific 

 coast states the roots are attacked rather than 

 the leaves, and here the insect is serious, its 

 work resulting in the death of the vines. The 

 hce are small, yellowish, and soft bodied. 

 Winged generations are produced, which spread 

 the species to new fields. 



Fig. 285. — Work of the 

 Grape-phylloxera on 

 roots. Original. 



Fig. 



286. — Galls on grape leaf caused by the 

 Grape-phylloxera. Original. 



In control, in California, imported varieties are grafted on native 

 eastern stocks, thus securing practical immunity. Infested vineyards 

 are treated by flooding, applying water first for 10 days, just after the 

 picking season, again for a similar period a few weeks later, and for a 

 thirty-day period in winter. Vines grown in nearly pure sand are not 

 severely attacked. 



