INSECTS 



63 



insecticides. Insects do not breathe through their 

 noses or mouths, but they have little holes, or pores 

 placed along both sides of their bodies, and through 

 these the air passes in and out. When anything 

 clogs these breathing pores, they die. It has been 

 found that certain oils and powders will destroy in- 

 sects by smothering them. Oils may be mixed with 



Courtesy U. S. Dept. of Agriculture 



Fk;. 39. Apples from trees that were sprayed. No farmer can afford 

 to neglect his fruit crop. 



otlior materials so as to prevent damage to the plants 

 on which the insects live. Kerosene emulsion is 

 such an insect destroyer. Poisons may be put on 

 the plants before insects appear as a protection, but 

 contact insecticides must be applied to the insects 

 themselves. 



Moulting of Insects. Insects have no bones or 

 inside skeleton, but the skin becomes very hard and 



