THE GKAPE-BERKY MOTH. 63 



clusters it is ineffective against the larger portion of the first brood 

 of larvae, since at this time only a small portion of them have hatched. 

 On the other hand, it is of great importance to destroy as many as 

 possible of these early appearing larva?, since the adults into which 

 they develop deposit eggs for the second brood. With our present 

 knowledge that the majority of the larvae of this first brood do not 

 appear until after the berries have set, this first poison application 

 previous to blossoming can no longer be emphasized as the most 

 important spray treatment, to the extent of regarding later applica- 

 tions as of little value or of withholding them entirely. In fact, 

 with the knowledge that the majority of the larvae hatch after the 

 blooming period during the first two weeks in July, additional atten- 

 tion should be given to making the spray application very thorough 

 during this period. It is quite probable that a single poison-spray 

 application just before the blossom buds open, followed by a heavy 

 double application about the first week in July just after the berries 

 have set and at a time when the maximum number of larvae are 

 hatching, will doubtless give the most satisfactory results to be 

 secured from a spray treatment. A study of the experimental 

 results secured in the season of 1908, when this heavy double-appli- 

 cation method was followed, indicates that better net results were 

 secured from these double-spray applications than in the seasons 

 of 1907 and 1909, when the plan of making a single application at 

 each date of spraying was followed. 



Where these heavy double-spray applications are resorted to it is 

 suggested that a Bordeaux formula consisting of 3 pounds of lime 

 and 3 pounds of copper sulphate to 50 gallons of water be employed 

 instead of 5 pounds of lime and 5 pounds of copper sulphate as is 

 sometimes recommended. The reason for suggesting this weakening 

 of the Bordeaux formula is that injury to the foliage of the grape- 

 vine has been observed to result from very heavy and frequent 

 applications of the stronger formula. 



In making spray applications against this insect it is very desirable 

 that a high pressure be maintained in order to force the poison spray 

 into the cluster so that all of the berries may be covered. (See PL 

 VIII, fig. 1, showing size of grape berries at date of second spray 

 application, at about the time many of the first-brood eggs of the 

 grape-berry moth are deposited.) If at the second spraying this can 

 not be done with a stationary nozzle arrangement on account of the 

 dense foliage, the trailer method of application used against the 

 grape leafhopper may be employed. (See PL VIII, fig. 2.) 



When the grape leafhopper is at all numerous in vineyards where 

 spraying treatment for the grape-berry moth is necessary, a combi- 

 nation spray may be used against both insects during the early 

 part of July, using the " trailer'' method of application. 



