4io POPULAR SCIENCE MONTHLY 



cially dark color, very useful in Australia for the destruction of various 

 scale insects, was introduced by Koebele into California while on his 

 second mission to Australia in 1893. It naturalized itself and plays 

 an important role in fighting the black scale of the olive. A hundred 

 thousand of these insects were distributed in different districts. In 

 different localities they multiplied in a prodigious way, and proved to 

 be particularly efficacious in the moist climate of the seashore. Mr. 

 Cooper, president of the State Board of Horticulture, had such confi- 

 dence in the efficacy of this RMzobius and other ladybirds that, yielding 

 to a perhaps exaggerated enthusiasm, he renounced for a time all other 

 intervention, and, in order to allow them to multiply at their ease, he 

 suspended all treatment. According to him, to spray trees upon which 

 there is Rhizobius is a crime and should be severely punished. 10 



Attempts to Fight the San Jose Scale by Means of Ladybirds. — 

 The disasters caused by an insect commonly known as the San Jose 

 scale in the United States are well known. The damage done to the 

 fruit trees can only be compared in intensity to that done in our 

 country by the Phylloxera, and about 1898, the fear that it would be 

 introduced into Europe occasioned prohibitory, special legislation on 

 the part of European states. Since it was a scale insect, it was natural 

 to search for an enemy which would approximate the role of Novius 

 cardinalis, but no one knew the original home of the San Jose scale. 



Australia was considered for some years as responsible. Finally, 

 they concluded that it might be Japan, and Mr. Marlatt, first assistant 

 of the Division of Entomology, Department of Agriculture, was sent 

 on a mission, in 1901-2, to the extreme orient to solve the question, 

 and he established in a positive manner the fact that the original home 

 of the San Jose scale was the north of China, where he found it occur- 

 ring upon small wild apple trees, in the mountainous country. There 

 he found, at the same time, with the scale insect a ladybird, Chilocorus 

 similis Eossi, which, both in the larval and adult stages, feeds on the 

 San Jose scale. This ladybird is an insect widely spread, not only in 

 China, but throughout all of Asia and the south of Europe. The San 

 Jose scale is, then, not its only food, but it can live at the expense of 

 different scale insects. Therefore, samples of this insect, coming from 

 China and offering the best possible conditions for adaptation to the 

 struggle against the San Jose scale, were sent to Washington, and all 

 precautions being taken, they were bred with great care in the Bureau 

 of Entomology, first in cages and afterwards in an experimental orchard. 



They were thus produced in sufficient quantity, so that for several 

 } ears they could be sent to different States. The colonies which were 



10 The attempt to acclimatize Rhizobius ventralis in India and Ceylon, 

 undertaken by Froggatt and Green, did not succeed, probably on account of 

 unfavorable climate. 



