616 USEFUL INSECTICIDES 



Poison, as in the case of insects which obtain their food by suck- 

 ing, as bugs in general. Some contact poisons also kill by 

 Asphyxiation, i.e., by forming a coating around the insects, thus 

 preventing their breathing; scale insects are affected chiefly in 

 this way. Generally speaking, the remedies for aphis (green-fly, 

 etc.) are in the nature of a contact poison, as emulsions, tobacco- 

 juice, etc., while for beetles, caterpillars and grasshoppers, stomach 

 poison, such as " Paris Green/' " London Purple," etc., are 

 more effectual. Insecticides in liquid form (with water) may be 

 applied by a fluid sprayer or a syringe capable of emitting a line 

 spray or mist, distributing the liquid evenly over the whole 

 plant; while those in the form of powder, mixed with lime, dust, 

 flour, etc., may be dusted from a powder-sprayer or bellows. 



Arsenate of Lead. (Sugar-of-lead). This compound is con- 

 sidered to have special advantages over " Paris green;" it is much 

 lighter than the latter, does not scorch the foliage, and can 

 therefore be used more freely. Satisfactory results have been 

 obtained by using from 1 to 2 Ib. of arsenate of lead to 

 150 gallons of water. The following formula is recommended : 

 Acetate of lead 2\ oz., arsenate -of soda 1 oz., water to make up to 

 10 gallons. Place the materials in the water and stir till dissolved, 

 when it is ready for use. One pound of treacle may be added 

 to render the mixture adhesive. 



Arsenate of Lime. As a substitute for the above the follow- 

 ing may be used: 1 Ib. arsenic, 4 Ib. washing soda, and 2 gallons 

 water. Boil till dissolved. Make up to 4 gallons with water. 

 Add one pint of the mixture to 4 gallons of water, and add to 

 this 4 oz. unslaked lime. 



Borer Wash. 1 pint crude carbolic or phenol; 2 Ib. soft soap 

 or hard soap 2i Ib.) ; 1 gallon hot water. Dissolve the soap in hot 

 \vater, and add enough clay to thicken it. 



Carbon Bisulphide. A highly volatile and inflammable clear 

 liquid, the vapour of which is given off at a low temperature and 

 is fatal to insect life. It is used successfully in the destruction 

 of ground-insect pests, where these are numerous or in colonies, 

 as in the case of termites. The poison is best applied to termites' 

 nests by saturating bolls of cotton wool with it, and dropping one 

 of these in each burrow, the latter being then quickly closed up. 

 The vapour, being heavier than air, sinks to the bottom of the 

 crevices and permeates the whole " nest." 



Caustic Soda. A white solid substance, very soluble in water, 

 acts as a caustic, is powerfully alkaline, and is deliquescent on 



