GRAPEVINE ROOT WORM 75 



in a more healthy condition, but this is true also where none of 

 these insecticides were used, beetles appearing later and in less 

 numbers than for several years." Professor Webster, at the 

 writer's request, has commented on the above experiments as 

 follows. He states that early results though satisfactory were 

 not thought by him to be conclusive and that a marked decrease 

 in the number of the beetles, vitiated later experiments to some 

 extent, so that he did not consider them as either conclusive in 

 themselves or as disproving the earlier work of Mr Mally. He 

 states that arsenate of lead must be tried thoroughly several! 

 times where conditions are such as to enable one to obtain de- 

 cisive results either one way or the other before it will be safe 

 to make definite statements. Professor Stinson reports only 

 fair success in destroying the beetles with poisons in Arkansas. 



It seems very probable, therefore, that some of the Ohio 

 growers have been led to attribute the relative scarcity of these 

 beetles to the use of poison whereas it may have been due 

 almost entirely to natural conditions. 



The beetles apparently ate the poisoned foliage almost as 

 readily as the unpoisoned in our breeding cages, and nearly the 

 same results are reported by Professor Mally. They are 

 voracious eaters and it would therefore seem as though they 

 would be amenable to this treatment, provided the insecticide 

 is on the vines at the time the beetles appear. Even if they 

 are not killed in the first three or four days, our studies of the 

 egg-laying habits show that if the adults are not destroyed for 

 a week or more, they would be prevented from depositing a 

 large proportion of their normal quota of eggs. 



The evidence at hand is altogether too little to warrant the 

 statement that poisons are of little value against this insect, but 

 it seems probable that these substances will be found efficacious 

 only when they are applied most thoroughly and under favorable 

 conditions. We can not under present conditions feel the con- 

 fidence of some earlier writers in poison sprays for this insect. 



Mr T. S. Clymonts states that in his experience spraying with 

 bordeaux mixture has proved of some benefit, since the beetles 



