THE WAR ON INSECTS 



275 



Arsenate of lead comes in paste form only, at present 

 writing, and cannot be applied dry.* Paris green can be 

 mixed with air-slacked lime or dry hydrate and applied 

 with a bellows, and for cases where a powdery dusting 

 will form as satisfactory a coating as a spray, the appli- 

 cation in that manner is just as good. There are cases, 

 however, as where an insect feeds only on the under- 

 side of a leaf, where a dust does not and cannot cover as 

 well as a spray, and others where the material must be 

 forcefully applied so as to get into a crevice or cavity 

 in order to secure a maximum effect. 



There are preparations of white arsenic which can be 

 made at home, forming combinations with lime which 

 are stronger and cheaper than either Paris green or 

 arsenate of lead; but these are dangerous in unskilled 

 hands and require so much care in preparation that 

 they are not advised, save when very large quantities 

 of material are needed. 



It is very often desirable to combine an insecticide 

 and a fungicide so as to prevent injury from disease as 

 well as insects, and Bordeaux mixture is the fungicide 

 generally used with either Paris green or arsenate of 

 lead. This Bordeaux mixture is in itself very offensive 

 to many insects and some of the flea beetles will scarcely 

 touch a plant protected by it. If the arsenical insecti- 

 cide is added to the fungicide in the same proportion 

 as if it were water, an extremely effective material is 

 obtained. The Bordeaux mixture is prepared as follows: 



Copper sulphate 4 pounds 



Quick-lime, stone or shell, good quality .... 4 pounds 

 Water 50 gallons 



Dissolve the copper sulphate in one gallon of hot 

 water, slack the lime in water sufficient to do it well, 

 and strain. These are the stock mixtures and will 



* A dry powder has been produced, but is still in the experimental stage. 



