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JOURNAL OF ECONOMIC ENTOMOLOGY 



\Yol. 8 



t unity to increase until for a time they were very abundant, but later 

 became scarce, corresponding to the scarcity of the borers brought 

 about b}^ them. In many places it is now difficult to find injury by 

 borers where formerly much cane was injured, and similarly the tachi- 

 nids are difficult to find in these places. 



Fruit-fly Parasites 

 Several species of fruit-fly parasites were brought from Africa and 

 Australia by Dr. F. Silvestri in 1913. Some of these were reared suc- 

 cessfully in large numbers and widely distributed. The following 

 year two species {Opius humilis from Africa and Diachasma tryoni 

 from Australia) were found to be established and quite wideh^ spread. 

 In 1914, Mr. D. T. Fullaway brought several more species of fruit-fly 

 parasites from Africa, which have likewise been reared in large num- 

 bers for distribution. It has not yet been long enough to expect exten- 

 sive results from these introductions, but there is hope that when sev- 

 eral of them are well established and generally spread much good will 

 result. 



In this short paper only the more important of the introduced bene- 

 ficial insects have been mentioned. There have been many others of 

 less importance, either by reason of their attacking less important 

 insect pests, or that they failed to increase in sufficient numbers to be 

 of significant value. There have been manj^ tried which for climatic 

 or other reasons entirely failed to become established. Manj^ attempts 

 have been made to find and introduce useful natural enemies for the 

 horn-fly on cattle, but none of them so far introduced have brought 

 about any noticeable general reduction of the pest. 



The entomologists of Hawaii, encouraged by those which have been 

 successful, are continuing in this method of combating insect pests, 

 and from one or the other of the institutions there, projects for the 

 introduction of more beneficial insects are continually being carried on. 



Mr. E. D. Ball: What is the native home of the sugar cane leaf- 

 hopper? 



Mr. 0. H. Swezey: It was supposed to be in Australia. Para- 

 sites were secured from there, also from Borneo, New Guinea and 

 Fiji. We are not certain of the native home of the leaf-hopper. It 

 is not a pest in the countries mentioned. 



Dr. L. O. Howard: Hawaii has done more than all other countries 

 put together in the matter of introducing parasites successfully. The 

 introduction of insects to feed upon weeds or other plants is a dan- 

 gerous experiment and it is very fortunate that it turned out so well 

 in this case. 



