6o 



NEW YORK STATE MUSEUM 



and there it has multiplied so freely as to nearly destroy the 

 vines. 



Experiments with arsenical poisons. The results obtained with 

 these substances last year are given in detail in our report for 1904. 

 The work of 1905 in this direction has consisted largely in making 

 supplemental observations upon the areas sprayed last year. A 

 somewhat peculiar and anomalous condition was found to prevail 

 about the middle of June in our experimental area in E. ,W. Skin- 

 ner's vineyard at Portland. It was found that the grubs were 

 then decidedly more numerous under sprayed vines than they were 

 under those which were untreated last year and employed as checks. 

 This condition was exactly the reverse of what was found the pre- 

 ceding fall and may be explained in one or two ways. The appli- 

 cation of arsenate of lead protects the vines to a considerable ex- 

 tent, not only from insect injury but from fungous troubles and as 

 a result there was fully as good leaf development on the sprayed 

 vines as elsewhere. The well known preference the beetles exhibit 

 for a thick shelter might naturally lead them to oviposit more 

 largely on the sprayed vines and, owing to the fact that the last 

 of June and early July the foliage was pretty well protected by 

 poison, it may be that a considerable proportion of the eggs were 

 deposited in this area later, and this was borne out by our examina- 

 tions for egg clusters in 1904. A reference to our report for that 

 year will show that a high percentage of eggs were laid on the 

 sprayed areas late in the season. Grubs from these late deposited 

 eggs are not likely to attain full growth in the fall and as a conse- 

 quence are much more easily overlooked, so that the apparent dis- 

 crepancy between conditions found in the fall of 1904 and the 

 spring of 1905 may have been due in part to the better development 

 of foliage attracting more beetles, and in part to the failure of the 

 grubs to attain full size before final counts were made in October 

 1904. It is at least a peculiar condition, and there is a possibility 

 that some of the grubs found under the vines sprayed the preceding 

 year may have come from eggs deposited by inflying beetles since 

 we know that such migrations occur. 



Further evidence on this point, though not entirely of a satisfac- 

 tory character, was obtained by examining a vineyard near Pros- 

 pect Station where the beetles, in spite of four sprayings with 

 poisoned bordeaux mixture in which l /± pound of paris green was 

 used for each 50 gallons, had done considerable eating. This vine- 

 yard was treated primarily to prevent rot. The first application 

 was made just before and the second just after blossoming, the 



