those engaged in the cultivation of the soil should put the proper value upon the work 

 of economic entomologists, for they year after year see a large amount of their produce 

 destroyed under their very eyes by the ravages of injurious insects, thus rendering much 

 of their labour of no effect, and their incomes proportionately smaller ; they, too, have 

 happily learnt by experience that much of this loss may be averted by following the 

 advice of those specialists who devote their time to studying out the life-histories of their 

 enemies. 



Until recently there was what I will call a foolish fashion amongst scientific men to 

 scoff and sneer at the labours of those few who endeavoured to develope the economic 

 phase of Entomology. They did not believe, it was alleged, "in wasting time over 

 popularising science. If scientific study was to be valuable it must be technical ; there 

 was not time to dish it up in a diluted and palatable form for the masses." As a matter 

 of fact, however, we find that those who are continuously engaged in the practical 

 economic application of Entomology to the daily wants of mankind, have done just as 

 good work scientifically as any others ; and today we see that these ultra-scientists 

 find it advisable to keep their opinions to themselves, and day by day we find more and 

 more of the best scientific students throwing in their lot with those who only aim at 

 making their investigations useful and for the public good. 



That the dangers arising from the increase in numbers of injurious insects are 

 greater now than was formerly the case cannot, I think, be doubted. 



In all new countries larger and larger areas of land are continually being brought 

 under cultivation, and by growing large quantities of any one crop the farmer furnishes 

 those insects which feed upon it with a copious supply of food, and their numbers 

 increase correspondingly, A large supply of proper food is the main cause which affects 

 the amount of insect presence. The food of insects varies considerably, and embraces 

 almost all organic substances. Those which come under our consideration now are 

 mainly vegetable feeders. Of these some will feed upon a great many different kinds of 

 plants, belonging to various families or natural orders ; others, and these, luckily for us, 

 are by far the most numerous, will only eat a few, and these, too, must be plants of the 

 same or an allied family. Others, again, are so particular that they will actually starve 

 if they cannot obtain a certain species. In Nature we never find, as in our fields of 

 grain or roots, any one plant filling a large space, to the total exclusion of all others ; 

 but they are scattered here and there, several kinds growing together, consequently the 

 insects which feed upon any particular one of them have to search far and wide for their 

 food. This limited food supply is one of the checks which keeps their numbers down 

 to the proper limit. It has been estimated that every plant has an average of seven or 

 eight different insects which feed upon it. This number is probably too low, and some 

 of course are known to have many more than this. Dr. A. S. Packard states, in a little 

 work of which I shall speak later on, that the oak affords maintenance to between 500 

 and 600 species of insects, the hickory to 140, the birch 100, the maple 85, the poplar 

 72, and the pine over 100. It iaay be safely stated that at least one-tenth of all the 

 plants grown as crops by farmers is annually destroyed by insects. The amount of loss 

 every year from this cause is so great, as shown by the instances where circumstances 

 permit of an accurate computation being made, that it would be inadvisable for me to 

 dwell upon the subject or to give many of the figures, for I fear you would not believe 

 me. I will, however, give a few instances which can be verified by those who wish to 

 do so. 



In 1SS2 the lowest value which could be placed upon the agricultural produce de- 

 stroyed by insects in the United States was $200,000,000. In Canada in one year the 

 wheat midge destroyed 8,000,000 bushels of wheat, and in 1884 the " clover-seed midge " 

 yed £650,000 worth of clover seed. In England in 1882 a single insect (the Hop 

 Aphis), which belongs to one of the ten families which attack the hop, injured the crop 

 to the extent of 813^000,000. 



Now, this enormous, and to a large measure unnecessary, waste can only be pre- 

 vented by a systematic study of the life-histories of the insects which cause it. The 

 habits or modes of life of insects are very various, and by no means always the same in 

 the different stages. We have some species, as the Blister Beetles, which feed upon 



