EXPERIMENTS FOR CONTROL. 
31 
leaves were readily sprayed. It is always difficult to spray thor- 
oughly, and any cultural method which will facilitate effective work 
is worth while. During the early part of the seasons of 1911 and 1912 
the mites were observed upon the lower leaves only and from there 
migrated upward. It is estimated that the stripped area contains 
about 40 or 50 leaves; taking the average number of mites as 42 
Fig. 7.— Hop vine tied high and not stripped; lower leaves difficult to spray. (Original.) 
per leaf for an average infestation, the theoretical number of mites 
that would be removed would be about 1,680 or 2,100 per vine. 
One hopyard which was stripped before the mites were above the 
point to which the vines were to be stripped was observed August 9. 
It was found that the infestation had been materially checked. 
It is believed that timely stripping of the vines and removal and 
burning of the infested leaves will severely check the infestation and 
in some cases where the yards are not filled with food plants will 
