176 



Pmiciples of Plant Culture. 



this class are difficult to control, 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 al- 

 kaline washes to these parts. Soft soap reduced to the 

 consistency of thick paste by a strong solu- 

 tion of washing soda, applied to the trunk 

 or branches, forms a rather tenacious coat- 

 ing 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 or pine tar, is 

 said to prevent the entrance of the round- 

 headed borer (306). Protect- 

 ing the trunk with straw or 

 lath, as recommended to pre- 

 vent sun-scald 

 (185) may tend 

 to keep out 

 these insects. fig. 75. fig. 73. fig. 74. 



Borers in thp ^"'' ^^' Card of tarred paper, for placing 

 about the stems of young cabbage and canli- 

 +-i»nTi1r oon nfton flower plants. Reduced one-balf. 

 uiuuii c<m u±ien ^j^ ^^ r^^^^ j^j, cutting the cards. 



Vio rloo+ymrorl V>i7 ^K*- '^5. Manner of using the tool. The 



ue ue6.iioyeu uy dotted lines show the position of the edge of 



probing their '""^ *<"" ™ ^"'^ p^p"- 

 holes with a flexible twig. 



312. Leaf -Miners often infest spinach and beets 

 grown for greens, rendering the leaves unfit for use. 

 For these insects we can offer no preventive measures 

 of established value. The application to the young 

 foliage of powerful odorants, as coal-tar water or a 

 solution of carbolic acid, may prove beneficial. 



