250 



NATURAL HISTORY. 



affecting the roots, and the others making galls upon the leaves. Those 

 which attacked the roots made swellings, and the more tender the roots, 

 the more quickly the plants succumb to the attacks. While these dis- 

 coveries were being made, the pest increased to an alarming extent, and 

 whole districts were obliged to give up the vineyards. It was soon found 

 that certain American stocks had immunity from the insects, and so 



Fig. 2?,o. — The grape-Phylloxera, enlarged, with roots of the vine damaged by its ravages. 



grafting on American plants was resorted to extensively and with good 

 results. Insecticides were also used, but the expense is too great. Another 

 remedy is submerging the vineyard with water for twenty-five or thirty 

 days in the autumn or a longer period in winter. 



The Phylloxera is a native of America, but most of our vines are not 

 subject to their attacks to any great extent. Attempts have often been 

 made to introduce European grape-vines into this country, but without 

 any great success ; and the inference is that the Phylloxera is the cause of 



