LETTER OF TRANSMITTAL. 



United States Department of Agriculture, 



Bureau of Entomology, 

 Washington, D. C, October 28, 1910. 



Sir: I have the honor to transmit herewith three manuscripts 

 comprising a report on an investigation of hydrocyanic-acid gas 

 fumigation of citrus orchards in southern California. The pre- 

 liminary report on the subject was published as Bulletin No. 79 of 

 this Bureau under the title " Fumigation Investigations in Cali- 

 fornia." The present final report is divided into three parts: I, en- 

 titled "Fumigation of Citrus Trees in California/' by R. S. Woglum, 

 a special field agent of this bureau, containing the main report on the 

 field investigations and discussing the various details of fumigation 

 procedure; II, a paper by Mr. Woglum, "The Value of Sodium Cyanid 

 for Fumigation Purposes; " and, III, one by Mr. C. C. McDonnell, Chief 

 of the Insecticide and Fungicide Laboratory, Bureau of Chemistry, 

 "Chemistry of Fumigation with Hydrocyanic-acid Gas." 



I recommend the publication of these manuscripts as Bulletin 

 No. 90 of the Bureau of Entomology. 



Respectfully, L. O. Howard, 



Entomologist and Chief of Bureau. 



Hon. James Wilson. 



Secretary of Agriculture. 



in 



