August, '11] MORRILL: WHITEFLY CONTROL 363 



ORGANIZED EFFORTS AS A FACTOR IN THE CONTROL 

 OF THE CITRUS WHITEFLY 



By A. W. Morrill, Phoenix, Arizona 



The problem of the control of the citrus whitefly has long been 

 generally recognized as more difficult than that offered by any other 

 citrus pest now established in the United States. This rating, 

 which has ver^^ properly been given, is clue to the power of flight 

 possessed by both sexes of the adult insects combined with most 

 of the worst characteristics as to habits, rate of multiplication and 

 destructiveness possessed by true scale insect pests. 



An important feature of the problem of whitefly control by means 

 of the methods at present available for general use — spraying and 

 fumigation — is that of extending the availability of these methods 

 by securing the necessary coordination of efforts among the owners of 

 neighboring citrus groves. Recent experimental work has resulted 

 in bringing the direct remedies mentioned within the reach of the 

 owners of isolated groves and of citrus growers in all locahties where 

 cooperative associations have been organized for combating the white- 

 fly. While it is true that the pest may be controlled by the intelligent 

 and persistent use of direct remedies under less favorable conditions 

 than these, there remains the problem of securing the best practicable 

 condition of control upon the most profitable basis. The writer is 

 confident that any such a condition or anything approaching it can be 

 brought about only through proper legislative enactments. Such action 

 on the part of the state legislatures may be effectively supplemented 

 by cooperative protective associations among the citrus growers and 

 also by fruit marketing organizations. It is the object of this paper 

 to present the ideas of the writer concerning these subjects, which ideas 

 have been derived from a general knowledge of citrus conditions in 

 the Gulf Coast States and more particularly from three years' connec- 

 tion with the whitefly investigations of the United States Department 

 of Agriculture in Florida. 



Losses from the Whitefly and Estimated Expense of Competent 

 Supervisory Organizations 



The citrus whitefly (Aleyrodes citri R. and H.) and the cloudy 

 winged whitefly {Aleyrodes nuhijera Berger) cause annual losses in 

 Florida, Louisiana and Texas amounting to at least one and one-half 



