52 INSECTS AND INSECTICIDES. 



Tobacco water, tobacco dust, soot, lime, hellebore pow- 

 der, dry guano, flour of sulphur, whale oil soap, and solu- 

 tions of saltpetre or salt are all insecticides. They must 

 be cautiously used ; their strength being graduated when 

 used in solution, according to the plant, and the insects to 

 be destroyed. This is best ascertained by actual experi- 

 ment. 



Insectivorous birds, lady bugs and toads are great de- 

 vourers of insects, and should always be encouraged in a 

 garden. The birds not only devour the living insects, but 

 also devour the insect eggs, of which they are very fond. 

 Lady bugs live upon the plant lice, and toads live upon 

 small winged insects, of which they catch, large numbers. 



