70 



abundant enough to make an impression upon any pest, let us encourage it 

 by every means in our power. In such studies we will find the key to many 

 problems in economic work undreamed of before the commercial importance 

 of applied entomology came to the assistance of the farmer, the gardener, the 

 merchant, and many other interested people. 



There is, however, neither sense nor reason in asserting that because one 

 breeds a number of parasites from some partiular pest that the pest is; 

 doomed. Every working entomologist has cabinets full of specimens of 

 insects that he has bred from other insects or galls all true parasites but 

 he also knows their limitations. 



In conclusion, I would say, let the whole question be judged on its results. 

 Allow that one or two experiments have shown perfect results ; yet because, 

 mealy bugs or scale insects in a restricted locality have once or twice been, 

 destroyed by parasites, that can be no reason why the parasite cure alone, 

 should be forced upon anyone. 



Its admirers should be perfectly honest ; and if a friendly-introduced insect 

 from which, rightly or wrongly, great things had been expected turns out on. 

 further tria.1 to be a failure, they should say so ; and they should never 

 proclaim results for a parasite till those results have actually been proved in 

 its adopted country, for the wisest can never be sure of the results of any 

 experiment. 



Economic entomology is a great commercial science, and those at work for 

 its far-reaching interests could do it no greater harm than by misleading or 

 unproved statements. 



I append some notes and the opinions of some of the leading entomologists: 

 of the world on the broad question of parasites. 



H. Maxwell Lefroy, Imperial Entomologist of India, says, in his " Indian 

 Insect Pests, 1906" : "Artificial use of Checks. A subject that has unfor- 

 tunately attracted general attention is the fascinating one of using one insect 

 to destroy another. We know that there are parasites, predators, and the 

 like, which destroy insect life. The inference is that we should be able to 

 check all our pests by this means. Entomologists have devoted great atten- 

 tion to this point, with an almost complete record of failure. In one instance, 

 under very peculiar conditions, success was attained, a ladybird beetle being 

 introduced to destroy a virulent insect pest. The particular conditions 

 in this case were that the pest was newly introduced, had no enemies 

 in the locality to which it was introduced, and could be traced to the 

 country whence it came. . : . . No parasite, no enemy, will entirely 

 destroy an insect that is established throughout India, and there is 

 no advantage to be gained by introducing fresh parasites. There is, also,, 

 no ground for believing that in the near future we shall be able to artificially 

 employ fungoid and bacterial diseases in the destruction of insect pests ; they 

 appear to require special climatic conditions (e.g., very moist heat), and this 

 places the matter beyond our control." 



Dr. James Fletcher (Entomologist and Botanist to the Dominion of Canada) 

 says, in speaking about scale insects (" The Report of the Select Standing 

 Committee, Orchard Pests, Insecticides, and Farm Weeds, 1906-7, page 121 

 Parasites ") : " It has always been a most attractive field of investigation, 

 for all entomologists to try and discover, in their original homes, and intro- 

 duce the parasites of insect pests, which have increased unduly when brought 

 into other countries without their natural enemies. Notwithstanding the 

 fact that some of the best investigators have engaged in this work, and much 

 time and money has been devoted to it, it has been found an exceedingly 

 difficult matter to establish thes3 useful friends in a new home ; and it would 



