66 



THE GEAPE ROOT-WORM. 



FIELD EXPERIMENTS WITH POISON SPRAYS AGAINST THE 



BEETLES. 



The most striking evidence of the value of a poison spray as a 

 direct kilhng agent of the beetles, however, was obtained by us in a 

 field experiment conducted at North East, Pa., June 30, 1909. At 

 this date our attention was called by Mr. Frank Pierce to the presence 

 of large numbers of grape root-worm beetles feeding upon a block 

 of several acres of vines planted that spring. These vines had been 

 planted on land from which the vines of the greater portion of an 

 unproductive vineyard had been removed early the same spring. 

 The owner, not being aware at the time that these vines had been 



Fig. 29.— Young grapevine, unsprayed, showing extensive feeding by beetles of the grape root- 

 worm. North East, Pa., 1909. (Compare with fig, 30.) (Original.) 



rendered unproductive by infestation by the grape root-worm, 

 decided to replant the area immediately with young vines. After 

 removing the old vines the ground was plowed and planted to the 

 young vines and the space between these vines was sown to peas. 

 Thus the soil was left uncultivated during the period between early 

 May, when the peas were sown, and July 1 . Consequently the root- 

 worm larvae which had infested the roots of the old vines were per- 

 mitted to perform their transformations undisturbed. On June 28, 

 when Mr. Pierce harvested the peas growing between the rows of 

 grapevines, he observed some grape root-worm beetles feeding upon 



