OF WASHINGTON. 121 



REMARKS ON A RECENT TRIP TO THE CITRUS 

 REGIONS OF CALIFORNIA AND FLORIDA. 



By C. L. Marlatt. 



(Author's Abstract.) 



The primary object of the trip was to organize an experi- 

 mental investigation of the hydrocyanic-acid gas process for 

 the fumigation of citrus trees in CaHfornia. Secondary ob- 

 jects were to note the conditions of the recent white fly inva- 

 sion of certain California districts, and, on the return, to 

 inspect and supervise the investigation of the white fly prob- 

 lem in Florida which is being conducted for the Bureau of 

 Entomology under the general field direction of Dr. A. W. 

 Morrill. 



In May, 1907, the white fly (Aleyrodes citri R. & H.) was 

 sent to the Bureau for identification by Mr. G. W. Harney, 

 horticultural commissioner of Marysville. Later, additional 

 samples from the same region were received from Mr. E. M. 

 Ehrhorn. This insect was found well established at Marys- 

 ville early in May by Mr. Harney, who identified it from 

 descriptions as the Florida white fly, and submitted specimens 

 also to Mr. Ehrhorn and later to this Bureau for confirmation 

 of this identification. The discovery of the white fly at Marys- 

 ville marked the first instance of the establishment of this pest 

 in California — an event long feared by the citrus growers of 

 that State. The natural range of the white fly in this country 

 has for many years been confined practically to Florida and 

 the States bordering the Gulf of Mexico, including the south- 

 ern strip of Texas. Its range has extended fairly well north, 

 however, and it has apparently been able to maintain itself 

 out of doors at points in Georgia and possibly in South Caro- 

 lina ; but in greenhouses its range is practically unlimited, in- 

 festing principally dwarf citrus plants. The opportunity, there- 

 fore, for its carriage to California is ample, and it may have 

 gained entrance with greenhouse stock from some northern 

 source rather than from Florida or the South. 



Marysville is situated a few miles north of Sacramento, and 

 at first the infestation seemed limited to this town, but toward 

 the end of the summer the white fly was discovered well estab- 

 lished at Oroville, in Butte County, some twenty-six miles to 

 the north of Marysville. The Marysville infestation was con- 

 fined to the town, and to yard trees or small garden orchards. 

 Oroville lies in a considerable orange district, and the white 

 fly had been carried from the town into several of the adjacent 



