178 Amenean Horficulfi(ral Socieiy. 



OX SOME OF NATURE'S METHODS OF SUBDUING INJURIOUS 



INSECTS. 



DY PROF. WILLIAM SAUNDERS, LONDON, ONTARIO. . 



It is ;i frequent source of wonder why certain species of injurious insects- 

 occur (luring some seasons in immense swarms, causing much alarm and 

 inliictinj; the greatest injury, while the next season, when one might reason- 

 ably expect, from their well-known fertility of reproduction, that their num- 

 bers would be vastly increased, they are found to be comparatively scarce. 

 In this intermitting manner we have invasions of army worms, canker worms, 

 span worms, tent caterpillars, grasshoppers, and a host of other injurious in- 

 sects, which defoliate our trees and vines, consume our field and garden crops,. 

 and sometimes, when these destructive creatures cover large areas of terri- 

 tory, they induce much human privation and want. 



It must be obvious to all who have given this question serious thought 

 that up to the present time, whatever may have been the devices and inven- 

 tions for trapping and destroying such insect hordes, any efibrts which have 

 been made by man for their destruction are comparatively insignificant, and 

 utterly fail to account for the wonderful oscillations between scarcity and 

 the greatest abundance in these several forms of insect life. To acquire 

 any true insight into the causes which bring about these remarkable vari- 

 ations we must pry into nature's secrets, and, looking behind the scenes 

 to which the view of the casual observer is limited, we shall find reasons for 

 thankfulness, in that a wise Creator has so nicely balanced the contending 

 hosts of insect life that when from any cause any one form obtains for a time 

 a preponderance, that particular form is so preyed on by rapidly increasing 

 hosts of insect enemies, aided by insectivorous birds, and sometimes by des- 

 tructive diseases, that decimation soon occurs, and the unnatural increase is 

 soon reduced within its natural proportions. The fecundity of insects is so 

 great that were the natural checks or undue increase in any injurious spe- 

 cies entirely removed, we should in most cases soon be compelled to abandon 

 the cultivation of those plants which such insects select for their food. 



We would not on any account be understood as belittling the agencies 

 which man can bring to bear on certain destructive insects; on the contrary, 

 we hold that the studjj^ and practical application of economic entomology is 

 of the greatest importance in every agricultural and horticultural commu- 

 nity, for, if we can by the use of judicious measures materially lessen the loss 

 which these visitations always occasion, a great saving will beeftected, far 

 more than sufficient to compensate for the labor or expense incurred. More 

 especially does this apply to fruit-growers, because their operations are con- 

 ducted within comparatively limited areas, and hence they can often with- 

 out much labor keep insect foes in subjection, which, if allowed to take their 

 natural course, would entail severe loss. It is, however, none the less true, 

 that where destructive insects of any sort have prevailed over large districts,. 



