Plants as Affected by Animal Parasites. 175 



bor 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 compounds are 

 well adapted (283). In eases 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 

 tool used for cutting them, and 

 jec^tag loisonoSs uqMds the manner of using the tool are 

 plants. *' """' °' shown in Figs. 73, 74 and 75. 



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

 not only the so-called borers that burrow within the 

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

 live between the surface of leaves, but also the insects 

 that pass their larval stage within fruits. Insects of 



* Pf-nnmiia hrasaicae. 



