70 INSECTS AND MAN 



peach trees, and the roads, temple grounds, and streets are 

 lined with cherry and plum trees, planted for their blossom 

 and not for their fruit, no San Jose scale occurred, except 

 where recent stock had been imported from America. 



An extensive exploration showed that Japan could not 

 be considered responsible for the scale; accordingly the 

 investigator's attention was turned to China. After various 

 detours Pekin was reached, and, as this city is the centre 

 for all the region lying to the north and west, the streets 

 devoted to the sale of fruit proved of considerable interest. 

 All the fruit is brought into Pekin in little two-wheeled 

 carts, or on camel back, and in the markets there is always 

 a representative collection of the fruits of Northern China, 

 principally from the hill region leading up to the mountains 

 separating China from Mongolia and Manchuria. Great 

 quantities of these fruits, native apples, pears, and a little 

 haw apple were examined peaches were out of season, 

 and a scanty but general infestation of San Jose scale was 

 discovered. As no foreign stock had been introduced, the 

 presence of the scale indicated that it was of native origin, 

 and its scattered nature pointed to the probability of its 

 being kept in check by natural enemies. Further investi- 

 gation showed that the special region where the scale 

 thrives is a region leading up to the mountains, comprising 

 the northern and north-eastern frontiers of China, and 

 bounded, on the north and north-east, by the vast Desert 

 of Gobi, and, on the south and east, by the great alluvial 

 plain of the Yellow River, where only cereals are grown. 

 The region, it will be seen, is much shut off, a fact that 

 probably explains why the scale has not become a world- 

 wide pest ages ago. It is thought that the insect was 

 introduced into California on the flowering Chinese peach, 

 probably imported from the nurseries of Dr Nevius, a 

 missionary who introduced apple-growing into the pro- 

 vince of Shantung. 



A tree badly invested with San Jose scale appears to be 



