THE ORANGE THRIPS. 
15 
ward to reach the lower surface of the leaves. The trees should be 
drenched until they drip freely. 
Especial care should be taken with the outside fruit as the thrips 
scar this badly, but cause little or no injury to inside fruit. 
Either chamber nozzles of the Cyclone type or Bordeaux nozzles 
i.iay be used. If the former are used, disks with holes of about ^ 
inch diameter will be best. Double nozzles can be used to advantage 
on large trees, and will save time. It is preferable to use two lines 
of hose as this will insure more thorough work than where four leads 
are used. A majority of orange growers fail to apply a sufficient 
number of gallons of spray per tree. The following table will show 
approximately the correct amount to apply, and will enable those 
intending to spray to estimate the quantity of spray material needed 
for the season : 
Table IV. — Quantities of liquid required in spraying for orange thrips. 
Age of 
trees. 
One application. 
Total gal- 
lons of di- 
luted spray 
per acre of 
100 trees, 
4 applica- 
tions. 
Gallons 
diluted 
spray 
per tree. 
Gallons 
per acre 
of 100 
trees. 
Years. 
2-3 
5-7 
8-10. . . . 
12-14... 
2 
4 
5 
8 
200 
400 
500 
800 
800 
1,600 
2,000 
3,200 
SUMMARY. 
The orange thrips, a minute, orange-yellow insect of the order 
Thysanoptera, curls the leaves and scars the fruit of citrus trees in 
the San Joaquin Valley of California, the southern California orange 
belt, and the Salt River Valley of Arizona. 
Although this insect has been known by its work for some fifteen 
or sixteen years it has but recently been described, and it has now be- 
come of serious economic importance in the orange belt of the San 
Joaquin Valley of California. 
The orange thrips has numerous generations yearly, its life cycle 
requiring approximately 20 days, and it is to be found upon the 
orange trees from March to November. 
It can be controlled by four sprayings of lime-sulphur solution 
combined with a commercial tobacco extract, which should be applied 
when the thrips become sufficiently numerous. Three applications 
should be made in the spring months to save the fruit and spring 
