82 ENTOMOLOGICAL NEWS. [March, 



DEPARTMENT OF EGONOMIG ENTOMOLOGY. 



Edited by Prof. JOHN B. SMITH, ScD., New Brunswick, N. J. 



Papers for this department are solicited. They should be sent to the editor, Prof. John 

 B. Smith, Sc.D., New Brunswick, N. J. 



The Grape Root-Worm.— Under this title Mr. Webster has pubhghed in 

 Bulletin No. 62. of the Ohio Experiment Station, an interesting experience 

 with Fidia viticida Walsh. This recalls, strikingly, my own experience 

 in the New Jersey vineyards when tlie "Rose-chafer" was the enemy 

 whose destruction was sought ; and after reading over Mr. Webster's 

 Bulletin I think I can understand his feeling of helpless anger and disgust 

 at having accomplished so little after so many trials. Briefly stated, the 

 adult beetle lays its eggs under any convenient shelter on the vine, in 

 little clumps or masses varying in number. The larva; hatch, drop to the 

 ground and make their way as best they can to the roots upon which they 

 feed. They live underground throughout the Winter and emerge as 

 adults the following June, when they feed upon the foliage of the grape. 

 The injury is done by the larvae feeding upon the roots and more or less 

 impairing the vitality of the vine in that way. The interesting feature of 

 Mr. Webster's experience is the fact that the arsenites acted so slowly and 

 unsatisfactorily upon the beetles, and we are brought face to face here 

 again with a very important fact in Economic Entomology which should 

 prevent us from positively predicting the action of given insecticides in 

 new cases. There seems to be no doubt now that arsenic acts very slowly 

 indeed upon some insects, and that certain species are able to dispose of 

 a comparatively enormous quantity without apparent trouble. Prof. 

 Fernald has given his experiences with the Gypsy moth caterpillars : My 

 own experience with " Rose-chafer" corroborates him as to the difficulty 

 in destroying by means of arsenic this particular species, while Mr. Web- 

 ster seems to have found something very similar with this grape root-worm, 

 or rather with its parent beetle. Comparatively few experiments seem 

 to have been made to prevent the beetle from getting into the ground by 

 the use of repellant substances. Lime was used in one experiment ; but 

 it must not be forgotten where lime is used, that after a day or two it 

 might just as well be so much dust of another character for all the insec- 

 ticide effect that it will have. Lime is an insecticide only when it acts as 

 a caustic, or it does only what any other extremely fine powder would do 

 under similar circumstances. There would have been a good deal more 

 chance of success if ground tobacco had been used, although even this 

 lasts, effectually, only a short time. Here, however, there would have 

 been this advantage: a watery extract of tobacco formed by rains, would 

 prove of insecticide value if it came into contact with the larvse upon the 

 roots. Bisulphide of carbon was used with only very moderate success, 

 and Mr. Webster calls attention to a fact that has not been mentioned, so 



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