Insects and Insecticides 



INTRODUCTION. 



The agriculturist has continually to contend with 

 two classes of organisms that injure his crops. The 

 first of these are the noxious insects, and the second, 

 the parasitic fungi. These foes annually destroy 

 many million dollars worth of produce in the United 

 States, a huge portion of which might be saved by 

 the timely application of the various methods of 

 prevention mid remedy that are now known. The 

 pages which follow are devoted to a consideration of 

 the more important of the first named of these ene- 

 mies — the noxious insects — and to the methods of 

 Inventing their injuries. 



Insects are distinguished from related animals by 

 having three pairs of feet, fitted for locomotion, at-' 

 tached to a body divided into three principal parts 

 — head, thorax and abdomen. A majority of them 

 are also characterized by undergoing during their 

 development a series of well-marked changes, or 

 transformations. Such insects exist in four distinct 

 stages, namely: (1) the egg ; (2) the larva or cater- 

 pillar ; (3) the pupa or chrysalis ; and (4) the adult 

 or imago. As an example of these changes we may 

 take the Celery Caterpillar, the transformations of 

 which are illustrated at Plate I. The adult butterfly, 

 a handsome, black creature, with yellow and blue 

 i 



