212 MANUAL OF AMERICAN GRAPE-GROWING 



often being injured seriously season after season in succession. 



These leaf-hoppers obtain their food by piercing the epidermis 



on the under side of the leaf 

 surface and sucking the 

 sap, and add further injury 

 by inserting their eggs un- 

 derneath the skin of the 

 leaf. The punctures greatly 

 decrease the starch-produc- 

 ing area of the leaf with 

 the result that the vigor of 

 the plant is lowered, and 

 the quality of the fruit de- 

 creased. 



The life history of the 

 leaf-hopper is very well 

 known. The eggs are de- 

 posited in June or early 



July, and hatch from June 15 to July 10 in New York, the 



season being earlier or later as one goes south or north. The 



young leaf -hoppers are wing- 

 less, the nymph stage, but 



reach the adult stage in late 



July and August, at which 



time many of them mate, and 



eggs are laid from which a 



second brood may develop, 



although usually only one 



full brood is produced in a 



season in the northern states. 



Figures 41 and 42 show the 



several life stages of the 



leaf-hopper. Insects which 



, , . FIG. 42. The fifth and the mature stages 



become adults 111 the latter O f the grape leaf-hopper. (Enlarged.) 



FIG. 41. First four stages of the grape 

 leaf -hopper. (Enlarged.) 



