THE ORANtJK TllRIPS. 



15 



ward to reach the h)\ver surface of the leaves. The trees shoiikl he 

 drenched until they drip freely. 



Especial care should he taken with the outside fruit as the thrips 

 scar this badh% but cause little or no injury to inside fruit. 



Either chamber riozzles of the Cyclone type or Bonleaux nozzles 

 may be used. If the former are used, disks with holes of about rii 

 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. — Quuntitia^ of liquid required in s:i)r(tifiii(j for orange tlirii)s. 



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 j'ears 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 ^larch 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 



