62 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. , 



In considering the results of the spray experiments presented in 

 the foregoing paragraphs the casual reader might infer that the 

 benefit derived does not offset the cost of the operation. Charging 

 the total expense to this particular insect, this would probably hold 

 true for the seasons of 1907 and 1909. The treatment for 1908 

 shows a cash increase in crop yield, however, which more than offsets 

 the cost of spray treatment for that season. It should be remem- 

 bered, too, that these spray applications serve to protect the grape- 

 vines against the grape rootworm and the fruit and foliage against 

 fungous diseases. For both of these infestations it is desirable to 

 make the spray applications at about the same dates that the appli- 

 cations are recommended to be made for the control of the larva? of 

 the grape-berry moth. Hence the additional expense involved in 

 the increased amount of spray material used in making applications 

 thorough enough to be effective in decreasing the infestation of the 

 grape berries by this insect is not very great. 



The cost of spray material and labor for each application at the 

 rate of about 100 gallons per acre was approximately $2 per acre 

 for each application. Furthermore, there is no doubt that the 

 poison-spray application covering the three seasons greatly reduced 

 the infestation throughout the vineyard, for at the end of the third 

 season's treatment the infestation was manifestly much less than 

 when the experiment was commenced. 



RECOMMENDATIONS FOR CONTROL. 



At the present state of our knowledge of the habits of this pest 

 and of the methods that have been suggested and employed for its 

 control it is impossible to recommend any one method which of 

 itself has given results that are as satisfactory as could be wished. 

 The life-history studies made during this investigation, which have 

 been discussed under that head, indicate that we have been in 

 error in assuming that there are three broods of this insect in the 

 Lake Erie Valley. According to Prof. Slingerland the first brood 

 develops in the blossom clusters and the recently set berries. The 

 summer or second brood develops on the green grapes during July 

 and early August and a partial third brood occurs in autumn. 



On the strength of these statements much emphasis has been 

 placed upon the importance and probable efficiency of a poison spray 

 applied to the vines just previous to blossoming to destroy the 

 larvae of the first brood which feed upon the blossom cluster. The 

 life-history studies made during this investigation, however, indi- 

 cate that only about 25 per cent of the spring moths emerge pre- 

 vious and up to the time that the blossom buds break into bloom. 

 Hence no matter how effective this first poison application may be 

 in the destruction of the larvae actually feeding upon the blossom 



