108 AMERICAJq- GRAPE GEOWIKG 



on the larger ones, nntil at last the root system literally 

 wastes away. 



'^ During the first year of attack, there are scarcely any 

 outward manifestations of disease, though the fibrous 

 roots, if examined, will be found covered with nodosities, 

 particularly in the latter part of the growing season. 

 The disease is then in its incipient stage. The second 

 year all these fibrous roots vanish, and the lice not only 

 IDrevent the formation of new ones, but, as just stated, 

 settle on the larger roots, which they injure by causing 

 hypertrophy of the j^arts punctured, which also eventu- 

 ally become disorganized and rot. At this stage the out- 

 ward symptoms of the disease first become manifest, in a 

 sickly, yellowish appearance of the leaf and a reduced 

 growth of cane. As the roots continue to decay, these 

 symptoms become more acute, until by about the third 

 year the vine dies. When the vine is about dying it is 

 generally impossible to discover the cause of the death, 

 the lice, which had been so numerous the first and second 

 years of invasion, having left for fresh imsturage." 



^^ The life-history of the Grape Phylloxera may be thus 

 epitomized : It hibernates mostly as a young larva, tor- 

 pidly attached to the roots of the vine, and so deepened 

 in color as generally to be of a dull brassy-brown, and, 

 therefore, with difiiculty perceived, as the roots are often 

 of the same color. "With the renewal of vine growth in 

 the spring, this larva moults, rapidly increases in size, and 

 soon commences laying eggs. These eggs, in due time, 

 give birth to young, which soon become virginal, egg- 

 laying mothers, like the first ; and, like them, always re- 

 main wingless. Five or six generations of these partheno- 

 genetic, egg-bearing, apterous mothers follow each other ; 

 when — about the middle of July, in this latitude — some 

 of the individuals begin to acquire wings. These are all 

 females, and like the wingless mothers, they are partheno- 

 genetic. Having issued from the ground, while in the 



