141 
its disappearance 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 indcgenes. 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 Yedalia 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 How from the introduction of beneficial 
species, and an illustration is afforded in the Oapri-figinsect, 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 viticola, 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. 
The paper was discussed by several members, 
