TEE SAX JOSE SCALE. 307 



gained lodgmeiil in Europe bo Ear, and the chances arc that it' it should 

 do so the climate of Europe is so unfavorable that it would not be 



nearly so mischievous there as in America. 



The explorations, which are briefly narrated in this paper, wen; 

 undertaken to discover the native home of this scale insect, which was, 

 prior to 1901, a mere matter of conjecture. The desirability of dis- 

 covering the origin of this scale pest arose from the now well-known 

 fad that wherever an insect is native it is normally kept in check by 

 some natural means, and as a rule by some predaceous or parasitic 

 enemy. In the chance importation of foreign destructive insects to 

 our shores it very often happens that the natural check or enemy is 

 left behind, and the imported pest becomes in consequence much more 

 injurious here than in its native place. In a number of notable in- 

 stances in this country very great benefit has been derived by the dis- 

 covery and introduction of such natural enemies, thus reproducing the 

 conditions which obtain in the native home of the injurious insect. 

 The fluted scale and the Australian ladybird in California is the most 

 notable instance. The importation of this ladybird from Australia 

 has made citrus growing possible in California, and saves annually 

 many millions of dollars to that state. This and other similar cases 

 indicated the desirability of discovering the native home of the San 

 Jose scale, and the importation, if possible, of whatever natural means 

 were found there keeping it in check. 



Prior to this investigation there was a pretty well founded belief, 

 shared by Dr. Howard and the writer, that the San Jose scale was a 

 native of eastern Asia. "Without going into detail, this belief was 

 based chiefly on the ground that most other quarters of the world had 

 been fairly well investigated without any evidence of this scale insect 

 being found. It was known to occur in Japan, but the evidence rather 

 indicated that it had been recently brought to that country from the 

 United States in connection with the large shipments of nursery stock 

 from California to Japan during the last twenty-five or thirty years. 

 The itinerary, therefore, planned by the writer, with the advice of the 

 chief entomologist of the Department of Agriculture, Dr. L. 0. 

 Howard, was to include Japan, China and any other countries in 

 eastern Asia which it should prove desirable to visit. Six months were 

 devoted to a very thorough exploration of the different islands of the 

 Japanese empire, and three months to China, with shorter periods in 

 other regions. The explorations in China and Japan are the only 

 ones which bear especially on the San Jose scale problem. 



Explorations in Japan. 

 Durino- the time spent in Japan, from April to September, 1901, 

 the writer visited some forty-two provinces, and explored all the prin- 



