141 



its* (iisabpeariiDce may be attributed to some of the recent introduc- 

 tions from Australia.' 



The other law that is worth considering in this connection is that 

 experience has shown that, as a rule, the animals and plants of what 

 is known as the "Old" World i. e., of Europe and Asia when intro- 

 duced into North America have shown a greater power of multiplica- 

 tion than the indigenous species, and in a large number of instances 

 have taken the place of the native forms, which have not been able to 

 compete with them in the struggle for existence. The converse prop- 

 osition holds equally true, viz : that our species when taken to Europe 

 do not hold their own against the European indegenes. This is still more 

 true of the species introduced from the Old World, as well as from 

 America, into Australia, where the advantage of the introduced forms, 

 as compared with the indigenous, has been in many cases still more 

 marked. All other things being equal, therefore, we should expect the 

 species which are beneficial in Australia to be less so when brought to 

 this country, a deduction which brings out still more clearly the 

 exceptional nature of the case of Vedalia and Icerya, just as there are 

 some notable exceptions, as in the case of the Grape Phylloxera, in the 

 introductions between Europe and America. 



There are some instances in which there can be no doubt whatever 

 as to the good which would flow from the introduction of beneficial 

 species, and an illustration is afforded in the Capri-fig insect, Blastophaga, 

 psenes. There can be no question as to the good which would result 

 from the introduction of this species from Smyrna into those sections 

 of California where the Smyrna fig is grown without its intervention 

 and there are other similar instances which promise well and involve 

 no risk. But I have said enough to show that the successful utiliza- 

 tion of beneficial insects is by no means a simple matter and that dis- 

 criminating knowledge is required to insure success or prevent dis- 

 aster, especially in the second category dealt with in this paper. The 

 danger attending introductions of beneficial species by unconsciously 

 accompanying them with injurious forms, or by failure to appreciate 

 the facts here set forth, is well illustrated by the introduction to 

 Europe of our Peronospora mticola, of the English Sparrow to America, 

 and of the Mongoose to Jamaica. Wherever the importance of the 

 matter leads to legislation, what are denominated " political" methods 

 are apt either to control or in some way influence the resulting efforts 

 too often with unfortunate consequences. We should, as economic 

 entomologists, be on the alert for special cases where the introduction 

 or dissemination of beneficial species promises good results, and do 

 our best to encourage an intelligent public appreciation of such special 

 cases, while discouraging all that is of a sensational nature, as likely 

 to mislead and ultimately do our profession more harm than good. 



