66 
THE GEAPE ROOT-WOEM. 
FIELD EXPERIMENTS WITH POISON SPRAYS AGAINST THE 
BEETLES. 
The most striking evidence of the value of a poison spray as a 
direct killing 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 
