364 NEW YORK STATE MUSEUM ^' 



INJURIOUS INSECTS 

 Grape root worm 



Fidia viticida Walsh 



The following observations and experiments are a continuation 

 of those begun in 1902 and continued through 1903. They were 

 carried out under our personal supervision by Assistant Ivan L. 

 Nixon, who was in the field continuously for about two months. 

 The general results of the season's work may be considered as 

 strikingly confirming our earlier experiments and conclusions, and 

 better than this, in adding one more link to the evidence showing 

 that this serious insect pest can be controlled if energetic meas- 

 ures are promptly adopted. Our thanks are due to Messrs D. K. 

 Falvay and E. A. Skinner of Westfield, who kindly placed por- 

 tions of their vineyards at our disposal for experimental purposes, 

 and also to Mr E. W. Skinner of Portland, for the same courtesy. 



Attention is called to the fact that we have attempted to give 

 a precise idea of conditions so far as observations could determine, 

 preferring that to more ambiguous statements which may be influ- 

 enced by personal judgment. There is no guesswork for example, 

 about the number of insects actually taken from a vine when 

 jarred into a beetle catcher and carefully counted, while an estimate 

 is always open to question. It will also be noted that within 

 practical limits every possible means of estimating actual condi- 

 tions has been taken advantage of and our field observations con- 

 firmed wherever possible, by laboratory experiments. Others 

 have laid considerable stress on the number of egg clusters found 

 on a vine, and could we be sure of counting all deposited in a season, 

 this method affords an ideal way of estimating the activity of the 

 beetles. Unfortimately, the period of egg-laying extends over 

 two months, and it is hardly practical to determine the total 

 number of egg clusters normally laid on a vine, because the earlier 

 ones hatch before the later ones are deposited and the traces of 

 old egg clusters are so slight that they can be easily overlooked. 

 Several observations can hardly be made on the same vine, be- 

 cause the stripping of the bark, necessary to detect the egg clus- 

 ters, removes shelters and leads the beetles to deposit their eggs 

 elsewhere. Several counts at intervals of a week or 10 days are 

 necessary to the accurate estimation of the total number of eggs 

 deposited on selected vines, since experience shows that the pro- 

 portion of eggs on sprayed and unsprayed vines changes as the 

 season advances, and if this variation be disregarded, accurate 

 conclusions can not be drawn. 



