334 Report of the Horticultural Department of the 



insecticides. 



Insecticides when viewed from the way in which they cause the 

 death of insects fall into two general classes: (i) Poisons used 

 against insects having biting mouth parts and (2) contact remedies 

 used against insects having sucking mouth parts. These are con- 

 veniently grouped as follows: 



Poisons. 



I. Standard remedies: 

 Scheele's green 

 Paris green 

 London purple 

 Hellebore 



II. Commercial substitutes: 

 Paragrene 



Green arsenoid 

 Green arsenite 

 Pink arsenoid 

 Laurel green 

 Arsenate of lead 

 Disparene 



III. Home-made remedies: 

 Taft's arsenite of lime 

 Kedzie's arsenite of soda 

 Arsenate of lead 

 Arsenite of lead 



Contact Remedies. 



I. Standard: 

 Tobacco 

 Pyrethrum 

 Kerosene emulsion 

 Whale-oil soap 

 Lime-sulphur-salt wash 

 Hydrocyanic acid gas 

 Carbon bisulphide 



II. Proprietary: 

 Slug shot 

 Derror's fluid, etc. 



Some of the more important of these are hcie discussed: 



scheele's GREEN OR GREEN ARSENITE OF COPPER. 



One serious drawback to the use of paris green is that it settles 

 very rapidly when mixed with water and unless the pump is pro- 

 vided with the best of agitators it is difficult to maintain a spray 

 in which the amount of the poison is constant. Scheele's green is 

 superior to paris green in this respect as it is in the form of a very 

 fine powder which stays in suspension much longer than paris green. 

 On comparing mixtures of the same strength it was found that 



