174 



Principles of Plant Culture. 



age; root-eaters, those that devour the roots; and bur- 

 rowers, those that harbor within some part of the plant 

 by eating a passage for their bodies. 



308. The Leaf-Eaters include numerous species. 

 They are readily recognized by the fact that the leaves, 

 on which they feed, disappear more or less rapidly. 

 They may generally be destroyed by applying a poison 

 to the foliage, for which purpose the arsenical com- 

 pounds are well adapted (283). In cases where the 

 use of a deadly poison is unsafe, hellebore (289) or 

 pyrethrum (290) may be substituted. 



309. The Root-Eaters include fewer species than the 

 leaf-eaters and are usually more difficult to control. 



-. ;^ Carbon bisulfid, injected into the soil 



about the roots of cabbage and cauliflower 

 plants, with an instrument devised for 

 the purpose (Fig. 72), has been success- 

 fully used to destroy the cabbage maggot,* 

 and may be found useful in other cases. 

 Attacks of this insect have also been suc- 

 cessfully prevented by surround- 

 |". ing the stem of the young plant 

 with small cards of thin tarred 

 paper. One of these cards, the 

 [n tool used for cutting them, and 

 l j the manner of using the tool are 

 shown in Figs. 73, 74 and 75. 



310. Burrowers, as the term is here used, include 

 not only the so-called borers that burrow within the 

 stems and roots of plants, and the leaf miners, that 



* Phorbia brassicce. 



FIG. 72. Tool for 



plants - 



