56 THE BEBOBT OF THE No. 36 



products, an-d therefore do not yield the most, and sometimes any, calculable 

 advantage. In the latter case they often do even more harm than good in the 

 very things which were sought to be saved by their means." 



Perris and Decaux of France in the seventies and eighties advocated strongly 

 the use of parasites, and Berlese and Del Guercio of Italy, later recognized and 

 emphasized the value of entomophagous insects rather than insectivorous birds. 



In this conection it is interesting to note Silvestrfs own opinion. He says: 

 "I, for my part, believe that the usefulness and the harm of insectivorous birds 

 balance each other, and that more frequently the former may be superior to the 

 latter, considering things only from the viewpoint of immediate agricultural 

 interest." 



Insects and Animal Diseases. 



The relation of insects to animal diseases is now well known. The Anopheles 

 mosquito carries the malarial organism, the Stegomyia mosquito the yellow-fever 

 organism, the house-fly tubercular, typhoid fever and other germs, tsetse flies 

 the trypanosomes of the terrible "sleeping sickness" of Central Africa, rat-fleas 

 plague germs, lice typhus fever germs, etc. There is no longer any doubt as to 

 the inter-relationships that exist in this part of the web of life. 



Again, fishes furnish another link in the chain connecting mosquitoes and 

 malaria. As is well known, certain fishes feed upon mosquito larvae, and in many 

 districts are undoubtedly instrumental in regulating the amount of malaria. It 

 is believed that the presence of the small fish called "millions" in Barbados is 

 the reason why that island is so free from malaria. 



Babbits are not only a direct cause of great losses to the Australian farmers, 

 but also in directly developing the blow-fly pest which is very destructive. 



3. insects and Plants. 



We are familiar with the enormous losses produced every year by the action 

 of insects and fungous diseases on our cultivated crops. But we should not 

 fail to look at the other side of the shield, and ascertain how many plants are 

 dependent upon insects for their fertilization and the production, of seed. 



Elsewhere (In the Third and Fourth Reports of the Quebec Society for 

 the Protection of Plants) I have discussed the relations between insects and plants, 

 and their value as pollinators of useful plants. In this connection I may quote 

 Dr. Phillips' remarks regarding the value of the honey-bee : "The production of 

 millions of dollars worth of fruit depends largely on insect pollination, and no 

 insect is so important in this work as the honey-bee. It is a mo.st conservative 

 estimate to claim that the honey-bee does more good to American agriculture in 

 its office as a cross-pollinator than it does as a honey-gatherer." 



In the relation of insects to plant diseases, two aspects present themselves, 

 viz. 1, the ro'le of insects as disease-carriers to plants, and 2, the role of fungous 

 diseases in destroying insects,. 



It is clear that if these relations are to be thoroughly investigated, the 

 economic entomologist must work in close co-operation with the plant-pathologist. 



With regard to the part played by insects as disease-carriers to plants, I 

 cannot do better than refer you to the excellent paper by Prof. Caesar read at 

 the last meeting here (1918 Beport Ont. Ent. Soc), and to the article by Mr. 

 E. M. DuPorte in the 11th Beport of the Que. Soc. Protection of Plants (1918-1-9) 

 where the subject is fully discussed. 



