INSECTS 



and determine the best means of destrojdng the 

 one and protecting the other. The best means 

 of combating insects must be determined by the 

 manner in which they feed and by their life his- 

 tories. Insects that have biting mouth-parts are 

 destroyed by applying poison to the surface of 

 the leaves upon which they feed. Those which 

 have sucking mouth-parts must be treated by 

 remedies applied to their bodies. The most diffi- 

 cult to reach are the borers; they work in the 

 stems of plants and are most easily destroyed in 

 the egg stage. 



Some mechanical means of extermination are 

 hand-picking for the tomato arid other large 

 larvaB and tree-borers and collecting and destroy- 

 ing eggs of the tent-caterpillar. Paris green, or 

 some other poison, must be used in the case of 

 insects which have biting mouth-parts ; and lime, 

 salt, sulfur, kerosene emulsion, or some other 

 emulsion, is necessary for those insects which 

 have sucking mouth-parts and which would not 

 be affected by poison applied to the surface of 

 the leaves. Some insects are controlled more 

 easily in one stage of their life history than in 

 another. It would be more simple to destroy a 

 mass of tent-caterpillar eggs than the caterpillars 

 that come from the eggs, or the moths that de- 

 velop from the caterpillars. 



To combat insects most effectually it is neces- 

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