LEHER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Entomology, 

 Washington, D. C, June 11, 1908. 



Sir: I transmit herewith, for pubhcation as Bulletin No. 76 of this 

 Bureau, a report on fumigation for the white fly, as pdapted to Florida 

 conditions, by Dr. A. W. Morrill, special field agent. 



The investigation of the wliite fly problem in Florida is now in its 

 second year, and the results gained of immediate practical importance 

 are those which indicate best methods of control. Fumigation ^vith 

 hydrocyanic-acid gas during the short dormant period in winter, when 

 there are no winged insects, seems to afford the greatest measure of 

 control or possible extermination. Gas fumigation under the horticul- 

 tural conditions obtaining in Florida orange groves and the peculiari- 

 ties of climate presents rather a distinct problem. Tliis bulletin gives 

 the results of the fumigation experiments of two winters in Florida, 

 and demonstrates the entire applicability of tliis method of control to 

 the wliite fly. Tliis investigation has been under the general direc- 

 tion of Mr. C. L. Marlatt, Assistant Cliief of this Bureau, with Doctor 

 Morrill in field charge. The latter was aided during the winter of 

 1906-7 by Mr. Stephen Strong, formerly horticultural commissioner 

 of Los Angeles, Cal., and an experienced fumigator, and Mr. A. C. 

 Morgan, and during the winter of 1907-8 by Messrs. E. A. Back, 

 W. W. Yothers, and R. S. Woglum. 



The wliite fly is the big insect problem of Florida and other citrus 

 districts on the Gulf coast, and the information given in this bulletin 

 will be of immediate practical value to all citrus growers of the region 

 indicated. 



Respectfully, L. O. Howard, 



Entomologist and Chief of Bureau. 



Hon. James Wilson, 



Secretary of Agriculture. 



