U. S. D. A., B. E. Bui. 97, Part III. D. F. 1. I., May IT, 1U11 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



VINEYARD SPRAYING EXPERIMENTS AGAINST THE ROSE- 

 CHAFER IN THE LAKE ERIE VALLEY. 



By Feed Johnson, 

 Agent and Expert. 



INTRODUCTION. 



The rose-chafer (M acrodactylus subspinosus Fab.), in most of the 

 grape-producing sections of the eastern United States, is a vineyard 

 pest of long standing. It has been the subject of experimentation. 

 by numerous entomologists and horticulturists, who have employed 

 against it at some time or other almost every insecticidal substance 

 and method of combat in the whole category of insect remedies. In 

 spite of all this experimental work, however, there is considerable 

 skepticism among both vineyardists and entomologists regarding the 

 complete success of poison-spray applications when the beetles are 

 present upon the vines in large numbers. The results of vineyard 

 experiments against this pest with- a poison spray, undertaken by 

 the Bureau of Entomology in the Lake Erie Valley during the season 

 of 1910, have proved highly encouraging, although by no means final. 

 It is intended to verify this work during the coming season in the 

 hope that the efficiency of the poison-spray method may be put to the 

 severest test. 



Some of the chief factors militating against the obtaining of deci- 

 sive comparative data from sprayed and unsprayed portions of vine- 

 yards is the irregularity of infestation by the insect. This difficulty 

 is increased by the fact that in order to secure best results from 

 poison-spray applications it is very desirable that the poison be 

 applied as soon as the first beetles appear in order that their first 

 meal may consist of poisoned blossom-buds or foliage. Hence, unless 

 one has an intimate knowledge of the direction from which the bee- 

 tles invade the vineyard or the portions most heavily infested it is 

 exceedingly difficult to lay out plats which will give an accurate 

 comparison of the results of a spray treatment. 



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