GEAPE ROOT-WORM INVESTIGATIONS IN 1907. 67 



eggs or over; medium, when contiiining about ;W eggs; and .s/i/i/Il,, 

 when containing about 10 eggs. Examinations wore made in three 

 parts of the vineyard. An unsjDrayed check phit of 1 acre was left 

 on one side of the vineyard and the egg chisters found on 25 con- 

 secutive vines, at a date after the maximum number of eggs had been 

 dei:)osited, were recorded in the manner just described. A similar ex- 

 amination was made on 25 consecutive vines in the sprayed portion, 

 six rows over from the check plat, and a further examination on 25 

 sprayed vines on the opposite side of the vineyard, the main ol)ject 

 of this last examination being to determine the uniformity of egg 

 deposition throughout the vineyard. 



RECOMMENDATIONS BASED ON OBSERVATIONS AND RESULTS OF 



SEASON'S WORK. 



The work of the past season, at North P]ast, Pa., indicates that 

 thorougli and timely si)raying of infested vines with arsenate of lead 

 will, ])y preventing the deposition of a sufficiently high percentage of 

 eggs, reduce the number of grape root-worms to such an extent that 

 they will not seriously affect the growth of the vines. In order to 

 make the spray effective, however, the first application must be made 

 either innnediately Ix'fore, or as soon as the first beetle is seen in 

 the vineyard. 



Since the emergence of the beetles from the soil is governed largely 

 by weather conditions, especially those of temperature, no definite 

 date for making the first a[)plication can be given. For instance, the 

 records of Felt and Slingerland show that in normal seasons the 

 beetles commence to appear during the last week or ten days in June, 

 whereas, in 1007, none was found in vineyards by the writer until 

 July 15, although he had spent a large portion of every day in the 

 vineyards for a week or two preceding that date. Hence, it is very 

 necessary to watch the development of the larva^ and pupa^ in the soil. 



The emergence of the beetles in our breeding cages during the past 

 season coincides very closely with the appearance of the beetles in 

 vineyards. The first two beetles appeared in the cages on the morn- 

 ing of July 14 ; by the 15th a large number had emerged, and the same 

 day the beetles were very numerous on foliage in vineyards on gravel 

 soil. Xearly 50 per cent of the beetles which matured from 750 larva\ 

 placed in the soil in our breeding cages, emerged on the third and 

 fourth days after the first beetle appeared. This simultaneous emer- 

 gence of so large a percentage of beetles shows the necessity of having 

 the first spraj' application upon the vines by the time the first beetles 

 appear, or, at least, to have the spraying equipment in readiness so 

 that the a})plication may be made with the least possible delay. 



The time of emergence of the beetles can l)e determined quite closely 

 by examining the condition of the pupie in the soil every few days 



