86 THE GRAPE EOOT-WORM. 



TIME OF APPLICATION OF SPRAYS. 



Much time and labor is actually wasted in making spray applica- 

 tions after beetles have done considerable feeding and deposited 

 many of their eggs. The necessity of having all equipment and mate- 

 rial in readiness to make the first application as soon as the first 

 beetles appear can not be too strongly emphasized. There is no 

 doubt that the indifferent results secured from spraying by many 

 vineyardists is largely due to failure to make the first application as 

 soon as the first beetles appear upon the vines. 



Unfortunately no definite date can be set for the making of this 

 first application on account of the wide range in the date of emergence 

 of beetles from the soil from year to year, due to variations in sea- 

 sonal temperature conditions, especially during the spring months. 

 Our records show that the beetles emerged fully three weeks later in 

 1907 than in 1908 and spraying operations had to be planned 

 accordingly. 



Normally the first beetles may be expected to appear between the 

 20th and 25th of June. It should not be inferred, however, that the 

 insect does not exist in the vineyards in serious numbers if the 

 beetles are not in evidence at the latter date, for it happens that 

 even experts have been led astray, as occurred in Chautauqua County, 

 N. Y., in the spring of 1907, when experts visited the grape belt dur- 

 ing the first week in July and, finding no beetles at this date, inferred 

 that the pest no longer existed in very injurious numbers. Yet late 

 in July it was found that beetles had emerged in enormous numbers 

 in many vineyards throughout the area ' visited. This emphasizes 

 the fact that only by the closest observation can the vineyardist 

 determine the damage which this insect may inflict upon his vines 

 and he must be fully prepared every season to combat the pest on its 

 first appearance. A more detailed discussion of the changes in time 

 of emergence of the beetles from year to year is given under the head 

 of seasonal history of the insect. 



NUMBER OF SPRAY APPLICATIONS. 



During this investigation it has been learned that two thorough 

 spray applications will reduce this pest to numbers which will not 

 materially affect the health of the vine or the production of profitable 

 crops. The second application should be made about a week or ten 

 days after the first to cover the growth of new foliage which has 

 developed, and also to destroy those beetles which may not have 

 emerged from the soil at the time the first application was made. 

 Since rearing records indicate that the maximum number of beetles 

 emerge within the period of ten to fifteen days after the first beetles 

 appear (see fig. 23) the small percentage of late emerging beetles will 

 not be likely to effect very great injury. The fact that there is some 



