17 



the failures have undouhtetlly lieeti due to weak powder. It is not 

 at all poisonous, and hence is free from some of the objections 

 which some persons may make to the arsenites ; but at best it is 

 not so certain as they are. The pyrethrum lias the advantaj^e that 

 it is not necessary that it be eaten ; it destroys insects, if it does so 

 at all, by its contact with them. But on this account it is neces- 

 sary that it be very thoroughly applied, that it may at once reach 

 all the insects. For the green cabbage worm and other soft-bodied 

 insects it is to be recommended. 



CARBOLIC ACID. 



A dilute solution of carbolic acid (the crude dark sort which can 

 be bought for about seventy-five cents a gallon is good enough) is 

 very good as a remedy for plant lice, mealy bug and such like in- 

 sects. The strength may vary according to circumstances ; but it 

 cannot be used very strong or the foliage will be killed. One part 

 of acid and one hundred of water makes about as strong a mixture 

 as it is safe to use. An emulsion may be made with carbolic acid 

 instead of kerosene, and this is less likely to injure the foliage. It 

 may be made stronger than kerosene emulsion. Prof. Cook's for- 

 mula, which is certainly good, is as follows: One part of carbolic 

 acid to five or six parts of soap solution. As a remedy for bark 

 lice, borers, and the like, this is very highly recommended. It is 

 to be rubbed over the infested trees, or those liable to be infested, 

 about two weeks after they are in bloom. When it is desirable to 

 use a dry mixture, lime, plaster or any powder may be charged 

 with carbolic acid, one part in fifty well mixed, and then dusted 

 over the plants. Few classes of injurious insects are more difficult 

 to manage than those which remain in the ground the greater part 

 of their life. The white grub is of this sort, and many remedies 

 have been proposed and tried with more or less success, and for the 

 most part the success has been less. 



BISULPHIDE OF CARBON. 



At present the most promising substance which can be used for 

 the extermination of such insects is bisulphide of carbon. This is 

 a very volatile, ill-smelling liquid, exceedingly inflammable, but 

 not dangerous in any other way. Its value consists in its readily 

 becoming a vapor, which penetrates the soil immediately about the 

 the spot where the liquid is poured, and in the deadly efl'ect which 

 this vapor has upon insects. It is most easily used, all that is nee- 



