DISEASES AND INSECTS. 391 



continue their depredations until the fruit has 

 set. Where they are numerous, grapes become 

 very scarce. They seem to be somewhat migra- 

 tory in their habits. The only remedy that we 

 know of is to knock them off and kill them. 

 Vine Hopper or Thrips, (Tettigonia vitis^Fig. 

 155, enlarged four times,) This has 

 become one of the most formidable in- 

 sect enemies that the vineyardist has to 



Fig. 155. 



contend with. Its general appearance is 

 like that of a cicada or locust, but it is verj 

 diminutive in size, less than an eighth of an 

 inch, but as "lively as a cricket." It is of 

 a pale straw color or whitish yellow, with 

 two little red lines on the head. They be- 

 gin to appear in June on the under side of 

 the leaf, and are then wingless. As they in- 

 crease in size they shed their skins, and finally 

 become winged. They suck the juice from the 

 leaves, causing them to turn yellow, and un- 

 fitting them for their functions to such a degree 

 as to impair the ripening of both the fruit and 

 the wood. They sometimes abound in such 

 myriads that, if the vine be disturbed, it is 

 impossible to breathe without inhaling them. 

 Some of the remedies proposed for their de- 

 struction are altogether impracticable in the 



