C3 , r 483 



NUMBER MORE IMPORTANT THAN SIZE. 



It is woitliy of remark that by far the greater proportion of thethiin- 

 age caused by injurious insects is efiected by species of very small size, 

 whilst the large species are generally harmless. The two most serious 

 fruit insects, the Codling-moth and the Plum-curculio, are both below 

 the medium size, and the Apple bark-louse, the Apple-aphis, the Hes- 

 sian-fly, and the Wheat-midge, are so minute that they would not be 

 noticeable were it not for the ^'ide destruction which they cause to souie 

 of our most valuable crops, in consequence of their excessive multiplica- 

 tion. 



TREATMENT OF INJURIOUS INSECTS. 



For the details of treatment the reader is referred to the practical 

 treatises and reports which have been published upon this subject. We 

 can give here only an abstract of the methods to bo pursued. 



First, hand-picking and destruction by machinery, as in the case of 

 tlie Colorado potato-beetle ; second, poisoning by such substances as 

 Paris-green, hellebore, and carbolic-acid, as in the cases of the Potato- 

 beetle, and the Curraut saw-fly ; third, rendering their food distasteful 

 and repugnant to tliem by the application of such substances as ashes, 

 lime, and whale-oil soap, which are applicable to all foliage-eating in- 

 sects ; fourth, anticipating their attacks by planting at such times as 

 will cause the crops to sprout or to mature too early or too late for them, 

 both of which plans are exemi)lified by winter wheat, in its relation to 

 the Chinch-bug and the Hessian-fly ; and fifth, when all other means 

 fail, preventing their ravages by abstaining for a year or two from 

 raising the damaged crops. To these may be added, in certain favorable 

 instances, the transportation and colonization of friendly parasites. An 

 experiment of this kind has been performed by the author by the trans- 

 portation from the central to the northern parts of the State of Illinois, 

 of the minute Chalcis-fly which is parasitic upon the Oyster-shell Bark- 

 louse. 



The above list exhibits the most common methods of contending with 

 injurious insects, and these methods admit of almost indefinite modifi- 

 cation. But they can be most usefully described in connection with the 

 particular species of insect to which they are respectively applicable. 



USE OF LEARNED AND SCIENTIFIC TERMS. 



With regard to the use of scientific terms, derived mostly from the 

 Greek and Latin languages, it is to be remarked that though they may 

 appear difficult and forbidding, at first sight, the student soon becomes 

 familiarized with them and finds them to be almost indispensable by en- 

 abling him often to express in one or two words what would require a 



