HISTOET IN CALIFORNIA AND THE WEST. 15 



frontiers of China proper. Beyond the great wall on the north and 

 west lies Mongolia, consisting chiefly of the vast Desert of Gobi. To 

 the northeast, and separating the region from Manchuria and Korea, 

 is the eastern Gobi Desert. To the south and east lies the great alluvial 

 plain, the product of centuries of mud carried down by the Yellow 

 River, a region where cereals only are grown. These are all effective 

 barriers, and especially so when considered in connection with the 

 political conditions of the past. We have, therefore, as the original 

 home of this insect a naturall}^ shut-off area from which it could not 

 easily escape under the conditions prevailing up to our own times. 



The means by which the San Jose scale came from China to America 

 is a matter of interest. As previously stated, it is believed that this 

 pest reached California on trees imported by the late James Lick. 

 It is the writer's belief that Mr. Lick imported from China, possibly 

 thru Doctor Nevius, with whom he was probably in correspondence, the 

 flowering Chinese peach, and brought with it the San Jose scale to his 

 premises. Undoubtedly this scale insect came to this country in some 

 such way on ornamental stock from China. 



RECORD OF THE SPREAD OF THE INSECT. 



No attempt will be made to trace the details of the later extension 

 of the San Jose scale, but the earlier history of this scale in the 

 United States is well worthy of record as is also a summary at least of 

 the means by which it became so widely and disastrously distributed 

 so shortly after its first appearance on the Atlantic side of the 

 Continent. 



HISTORY IN CALIFORNIA AND THE WEST. 



The spread of the San Jose scale from the point of original infesta- 

 tion in the San Jose Valley was somewhat rapid, its area increasing in 

 every direction, but more rapidly toward the north and the west. By 

 1873 it had become a serious pest in orchards which had direct con- 

 nection with that of Mr. Lick, and in 1880, when Professor Comstock 

 studied it, he reported that he had never seen any other species so 

 abundant and injurious as this was in certain orchards. As reported 

 by Mr. Coquillett, it had extended as far west as San Francisco by 

 1883, but it had not reached important deciduous-fruit districts in 

 southern California three years later. Prior to its reaching the East 

 in 1886 or 1887 it had slowly extended its range on the Pacific coast 

 and in States west of the Rocky Mountains, including California, 

 Oregon, Washington, and Idaho on the north, and Nevada, Arizona, 

 and New Mexico on the south. In the earl}^ nineties it had penetrated 

 into British Columbia. 

 8449— No. 62—06 2 



