Plants as Affected by Animal Parasites. 167 



309. The Root-Eaters include fe\ver 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 successfully 

 used to destroy the cabbage maggot,* and may be found 

 useful in other cases. Attacks of this insect have also 

 been successfully prevented by surrounding 

 the stem of the young plant with small 

 cards of thin tarred paper. One of these 

 cards, the tool used for cutting them, and 

 the manner of using the tool aie shown in 

 Pigs. 72, 7.3 and' 74. 



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 

 (-^3^" live between the surface of leaves, 

 f^^--'''' but also the insects that pass their 

 larval stage within fruits. Insects 



Fig. 72. Tool for injecting 



poisonous liciuids about tiie of this class are difBcult to con- 

 roots of plants. \:^o\, since they are mostly beyond 

 the reach of insecticides. 



311. Borers that infest the trunks and main branches 

 of trees, may often be kept out by applying strong alka- 

 line washes to these parts. Soft soap, reduced to the 

 consistency of thick paste by a strong solution of wash- 

 ing soda, applied to the trunk or branches, forms a rather 

 tenacious coating which repels the female insect. Paint- 

 ing the trunks of small apple trees a short distance above 

 and below the surface of the ground with common paint 



* Fhorbia brassicce. 



