Pests and Diseases 193 



form to pupae in autumn and the change to the beetle 

 form takes place before winter, the beetles usually remain- 

 ing in a quiescent state until their emergence the following 

 spring." ^ 



Wireworms do not affect sugar-beets nearly so much 

 as they do some other crops. They are always worse 

 after sod, corn, beans, or potatoes. When once they get 

 into the land, they are diflBcult to eradicate by ordinary 

 treatments. Nothing put on the land will kill them with- 

 out also injuring the soil. One of the best ways is to starve 

 them out by summer fallowing or by growing crops on 

 which they do not feed. The elimination of trash from 

 the field also helps. 



Flea-beetles and leaf -beetles {Chrysomelidae). 



Several small leaf-feeding beetles, known as flea-beetles 

 and leaf-beetles, do considerable damage to sugar-beets. 

 The most severe injury is to young beets when they have 

 from two to eight leaves. Some of these insects cause in- 

 jury both in the adult and larval stage. The beetles 

 skeletonize the leaf by eating out the pulp between the 

 veins. These insects are sometimes poisoned by the use 

 of paris green, london purple, and paragrene applied dry 

 mixed with flour and dusted on to the leaves. Arsenate of 

 lead is an effective spray. Clean culture is also helpful. 



Grasshoppers. 



Grasshoppers are among the most common and the best 

 known of crop pests. They eat almost all kinds of plants 



' Chittenden, F. H., U. S. Dept. of Agr., Bur. of Ent., Bui. No. 

 43. 



