Uns. D:.-A., 8B. Ba Bulls of. Part tir. Dele. Noi ae Lui 
PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
VINEYARD SPRAYING EXPERIMENTS AGAINST THE ROSE- 
CHAFER IN THE LAKE ERIE VALLEY. 
By Frep JOHNSON, 
Agent and Expert. 
INTRODUCTION. 
The rose-chafer (J/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 numercus 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 he 
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. 
71419°—Bull. 9712 —5 oe 
