EXPERIMENTS FOR CONTROL. 
27 
During July the mites passed from larva to adult in 8 days and 
during April the incubation period was 7 to 10 days. 1 Basing the 
time of a second application on this data, 7 days was decided upon 
as the interim between the first and second sprayings, and by follow- 
ing out this plan some very encouraging results were obtained, as 
shown in Table VIII. 
Table VIII. — Experiments showing value of a second application in spraying for the red 
spider on hops. 
No. 
Date. 
Material. 
Applica- 
tion. 
Num- 
ber of 
mites 
pres- 
ent. 
Num- 
ber of 
mites 
killed. 
Per- 
cent of 
mites 
killed. 
Second 
appli- 
cation, 
per cent 
killed. 
1 
2 
3 
July 6 
July 19 
...do 
Lime-sulphur, 36° Baume, 1-86; flour paste, 
4-100. 
Lime-sulphur, 33° Baume, 1-70; flour paste, 
4-400. 
Lime-sulphur, 33° Baume, 1-70; flour paste, 
4-100. 
Thorough . 
do 
do 
593 
143 
509 
543 
142 
440 
90 
99.7 
86; 4 
97.1 
99.7 
92.9 
It will be noted that only from 0.3 to 7.1 per cent of the original 
number of mites present on the vines were present after the second 
application. The mites which hatched from the few eggs that 
remained were not sumcisnt to form the basis for a reinfestation and 
the work was accordingly considered satisfactory. 
Unfortunately some of the plats treated were covered with infested 
morning-glory vines, which were severely injured by the mites, and 
which later resulted in a migration that soon reinfested the hop- 
vines. Morning-glory was not present in one plat, however, and 
although the applications were made so late that the vines were 
severely injured, the results to be expected from such a plan were 
clearly proved. These vines were comparatively free from mites at 
the end of the season and had a much more healthy color than the 
vines in the adjoining plats which were used as checks. 
FORMULAS FOR SPRAYS. 
To prepare the flour paste, mix a cheap grade of wheat flour with 
cold water, making a thin batter without lumps; or wash the flour 
through a wire screen with a stream of cold water. Dilute until there 
is 1 pound of flour in each gallon of mixture. Cook until a paste is 
formed, stirring constantly to prevent caking or burning. Add suffi- 
cient water to make up for evaporation. (See PL VI, fig. 1.) 
For spraying with flour paste alone, use 8 gallons of paste as pre- 
pared above to each 100 gallons of water. 
For the flour-paste and lime-sulphur spray, use 4 gallons of paste 
to each 100 gallons of spray containing the lime-sulphur. 
1 In moderate weather allow 10 and in hot weather 7 days between applications. 
