INSECTICIDES, PREVENTIVES, AND MACHINERY. 433 



band, — smooth side, if any, to the trunk, — and then turn down 

 from the top hke an inverted funnel. This prevents a matting of 

 the inside of the funnel by rains and, under ordinary circum- 

 stances, forms a complete bar to the ascent of wingless insects. 



Finally, the most effective of all preventive measures is good 

 farming. Keep crops of all kinds in the most vigorous possible 

 condition, with plenty of readily available plant food, and in 

 orchards allow no dead wood of any kind to remain over winter. 

 Dead and dying branches should be cut, carted out, and burnt 

 ^efore the first warm spell of spring, and dying trees should meet 

 the same fate. There will be nothing to encourage insects to 

 come in, under such conditions, or to remain if brought in. The 

 term "good farming" has a wider application than I have made 

 here, but this subject has been incidentally referred to on other 

 pages, and needs no further elucidation here. 



CHAPTER IV, 



INSECTICIDES. 



Broadly speaking, insecticides are of two kinds — those that 

 kill by being eaten, or stomach poisons, and those that kill by 

 contact. Some substances, such as hellebore and tobacco, belong 

 to both categories ; but are most effective within their range as 

 contact poisons. 



Of the stomach poisons the various preparations of arsenic 

 stand first, and, indeed, arsenic forms the basis of all the insecti- 

 cides that kill by being eaten, so far as they are known to me. 

 The fact that some of the preparations are advertised as ' ' harm- 

 less " does not alter this, for they are "harmless" only because 

 the amount of poison is so small that under ordinary circumstances 

 it would be almost impossible for a man to eat enough of the 

 sprayed material to cause death. In almost all the insect-killers 

 that are to be applied dry, undiluted, and are sold under a fancy 

 name, from twenty to twenty-five parts of the bulk is make- 

 weight, — plaster, lime, ashes, and the like, — which are charged at 

 many times their value, and on which the farmer pays freight in 



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