ARID AGRICULTURE. 261 



or openings along the sides of the body. By 

 clogging up these pores we smother them to 

 death, or by using caustic solutions we may burn 

 the life out of them. For such bugs, therefore, 

 we use whale oil soap, or kerosene emulsion, or 

 tobacco juice, or smoke, or gas, or fine dust, like 

 Persian insect powder (Pyrethrum). For the 

 larger sucking insects, like the squash bug, the 

 most effectual method seems to be to hand pick 

 and kill them with a club. 



There are many slicking plant lice that live 

 on the roots of plants and cannot be reached by 

 sprays. Some of these, like the grape phyloxera 

 and others may be killed by injecting bisulphide 

 of carbon into the ground. The gas goes down 

 thru the soil and kills the insects, but does not 

 injure the plants. An effectual remedy for lice 

 on tree roots is to work a few pounds of pow- 

 dered tobacco into the surface soil around the 

 tree, then wet it down. Tobacco juice will kill 

 anything but man. 



INSECTS There are great numbers of insects that de- 



CHEW 



stroy crops by simply eating them. Such in- 

 sects as beetles, grasshoppers and caterpillars are 

 , examples. 



Insects that chew their food may be de- 

 stroyed with stomach poisons, at least where they 

 live on the outside parts of plants. The poisons 

 generally used are Paris green or arsenate of 

 lead. Sometimes the poisons do not work or are 



