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INTERNATIONAL CONGRESS OF VITICULTURE 



August in northern Ohio. These moths lay their eggs on the berries of the 

 grape clusters. The berries are almost grown, and at this season of the year 

 the eggs hatch in a very short time, certainly not more than three to five 

 days after they are laid. The larvae bore through the skin of the grape and 

 feed on the cells of the developing berry, sometimes just below the skin of 

 the berry. 



Fig. 5. Injury to young bunch by larvae. 



A few berries may have only a purple spot on their sides, but the charac- 

 teristicly injured berry slits open and is often reddish or purplish along the 

 side of the break. This freshly broken open berry is an ideal place for the 

 spores of the various rots of grapes to settle and grow. In some localities, 

 this injury has been attributed to the grape rots when the real trouble was 

 the first brood of larvae of the grape berry worm, which created ideal con- 

 ditions for the growth of rot fungi through the injury done to the berries. 

 The second brood of larvae bore into the almost full grown grape berries 

 partially cutting off the supply of nourishment to the cells above the injured 

 portion, and we have the purplish or reddish purple spot surrounding the 

 point of entrance and often extending over one side of the berry. This is the 

 typical injury noted by Riley in his Missouri reports, and in northern Ohio 

 is caused by the second brood of larvae. Riley describes this brood as 

 follows: "Its presence is soon indicated by a reddish-brown color on that 

 side of the yet green grape which it enters. On opening the grape a winding 

 channel is seen in the pulp, and a minute white worm with a dark head is 



