Jul. 903, U. S. Dept. of Agriculture. 



Plate IV. 



The Grape Phylloxera in California. 



Phylloxera vitifoliae: Fig. 1. — Phylloxera nodosities shown on Zinfandel grapevine: 

 a, Xodosities on terminal rootlet's; 6, nodosity showing Phylloxera feeding: c, adult louse; 

 d, molted skin of same. Fig. 2. — Phylloxera tuberosities on smaller root: a, Infested 

 portion of root: 6, normal portion of foot. Fig. 3. — Section of grapevine root showing 

 adult louse with eggs in situ. Fig. 4. — Sections of root infested: a, Newly formed tuber- 

 osity; 6, advanced stage of tuberosity; c, side view of older form of tuberosity; d, tuber- 

 osity causing the cracked condition of bark; e, young colony of insects as found on roots. 



