UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 645 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



Washington, D. C. 



January 26, 1918 



SOME REASONS FOR SPRAYING TO CONTROL INSECT 

 AND MITE ENEMIES OF CITRUS TREES IN FLORIDA. 



By W. W. Yothebs, 

 Entomological Assistant, Tropical and Subtropical Fruit Insect Investigations. 



CONTENTS. 



Gradual adoption of spraying „ 1 



Pests of importance 2 



Injury to trees and fruit 2 



The grading of fruit 3 



Reduction in size caused by insects 8 



Page 



Better grades of fruit bring better prices 13 



Spraying scheme for controlling citrus pests. 15 



Cost of spraying 16 



Profits and benefits 17 



Conclusion 18 



GRADUAL ADOPTION OF SPRAYING. 



Among Florida growers there have been developing during late 

 years what may be called two schools for the control of citrus 

 pests. One of these favors dependence upon natural enemies; the 

 other, upon artificial methods^ particularly spraying. The relative 

 merits of these two general methods of control are not discussed 

 here, since, as time passes, it becomes more and more evident that 

 there is room for both under the widely varying conditions sur- 

 rounding , Florida groves. Enthusiastic supporters of control by 

 natural agencies such as entomogenous fungi do not believe that the 

 lowering of the grade and the reduction in the size of the fruits and 

 of the yield, if any, are of sufficient importance to demand attention. 

 Or perhaps the case may be stated more fairly by saying that they 

 believe that it is more profitable to use no measures for the control 

 of pests, contending that it pays better to grow the lower grades 

 of fruit without treatment than the better grades with treatment. 



It is interesting, however, and very encouraging to note the gradual 

 adoption of a system of spraying for the improvement of orchard 

 conditions by men who, only a few years before the Federal Bureau 

 of Entomology began its demonstration work, believed in, and de- 

 pended upon, natural agencies as the best all-round method of con- 

 trol. This change has come partly through a realization that fungi 



21698° — 18— Bull. 645 1 



