186 The Sugar-Beet in America 



lambsquarter, and cocklebur, are breeding plants of many 

 of the most serious pests. Clean culture that would 

 eliminate these weeds greatly lessens the injury due to 

 insects. Rotation of crops is practiced by many of the 

 beet-farmers, but a few maintain the one-crop system until 

 the enemies of the beet become so numerous that the crop 

 no longer can be grown. ]\Iuch loss is occasioned by 

 planting beets after grass or similar crops that harbor 

 some of the worst beet enemies, such as the cutworms and 

 wireworms. Fields are not ordinarily kept as clean of 

 insect-harboring rubbish over winter as might be wished. 

 In sections w^here cutworms give difficulty it should be 

 known that plowing either in the fall or in the spring 

 lessens injury from this insect. \Mien attacks of insects 

 become acute, sprays and insecticides save much injury. 



Two general classes of insecticides are available: (1) 

 contact solutions for insects such as plant-lice and leaf- 

 hoppers, which obtain their food by piercing the plant 

 and by sucking its juice ; and (2) poisons applied in solu- 

 tion to the leaves of the plant to kill such insects as cater- 

 pillars, beetles, and grasshoppers, which feed on the out- 

 side of the leaves. The most effective contact spray is 

 made of a solution of tobacco. For biting or chewing 

 insects, sprays containing a poison such as the arsenicals 

 are employed, the insects being killed by eating a part 

 of the plant covered by some of the poison. The latter 

 type of spray should contain a very active poison which 

 will not easily run off the leaves of the plant and be 

 wasted, as frequently happens when not properly applied ; 

 hence arsenate of lead is one of the best sprays. 



Insect troubles vary from section to section; some of 



