INJURIOUS INSECTS. 



85 



is a variety of crops grown, perhaps what is known as knap- 

 sack spray pump is as con- 

 venient as any general pur- 

 pose machine. Where pota- 

 toes are grown on a large 

 scale, some special spray 

 pump that can be geared to 

 the wheels of a wagon is 

 probably the best to use. 

 Where insecticides are used 

 in powder form it is a good 

 plan to scatter them on the 

 plants through a coarse linen 

 bag or fine wire cloth. When 

 such material needs to be 

 ejected with force, a fan or 

 bellows may be used. It is 

 always best to use poisons 

 in a liquid form when practi- 

 cable since it is the most 

 economical and effective me- 

 thod of applying them. No 

 insecticide should ever be used 

 in a large way, until it has 

 been tried on a small scale 



Figure 33.— Colorado potato beetle in to see what its effect will be 

 all stages. jn , , , 



on the crop to be treated, 



since plants may be much more susceptible at one time than 



at another to applications of this nature. 



COMMON GARDEN INSECTS AND METHODS OF DESTROY- 

 ING THEM. 



The Colorado Potato Beetle (Boryphora decemlineata.)— The 

 Colorado potato beetle is so common and so well known by 

 every farmer and gardener in this country that it needs no de- 

 scription here. It came originally from the Rocky Mountain 

 region where it fed on the native sandbur (Solarium rostratum) 

 which is close allied to the potato, but when this insect came 

 to know the cultivated potato it preferred it to its original 

 food and has since become a very dangerous pest to this 



