CONTACT INSECTICIDES 



313 



Plant lice are sucking insects which attack many plants (Fig. 219). 

 It is evident that insects obtaining their food from the inside of 

 the plants can not be poisoned in the same way that we would 

 poison those eating the surface. An entirely different plan of com- 

 bating such insects must be used. Contact sprays are applied. 

 This means that the spray material must come directly in contact 

 with the bodies of the insects in order to kill them. 



Contact Insecticides. — Among the contact insecticides are the 

 soluble or miscible oils, lime-sulfur compounds, soap mixtures, 



Fig. 218.- 



-Canker worms feed on apple blossoms and on the leaves, 

 arsenate of lead. (Ohio Station.) 



Spray promptly with 



resinous emulsions, kerosene emulsion and crude oil emulsion. 

 Sulfur and nicotine sulfate may also be used as contact insecticides. 

 Pyrethrum, tobacco dust, road dust and other materials are some- 

 times used. 



Kerosene emulsion is one of the oldest and one of the most 

 effective home-made remedies for sucking insects. It is used com- 

 monly in fighting plant lice and all sucking insects with soft bodies. 



Prepare a soap solution of kerosene emulsion by using laundry- 

 soap, one-half pound, two gallons kerosene and one gallon of water. 



