618 USEFUL INSECTICIDES 



other arsenite compounds, it should be applied in the form of a 

 fine spray, the liquid being meantime kept constantly stirred, 

 and regulated in strength according to the nature of the plants 

 sprayed. 



Quassia, or Bitterwood. A vegetable insecticide, -consisting 

 of the bitter principle of the tree Picrcvua cxceha, which is fatal 

 to may forms of sucking-insects, particularly aphides. For use take 

 1 Ib. quassia chips, 1 Ib. soft-soap, 10 gallons water. Boil the 

 quassia with half the soap and half the water for one hour, strain 

 off the liquid and boil the residue for another hour with the 

 remaining soap and water- Mix the whole together, and make 

 up to 10 gallons with water. Never spray trees or plants bearing 

 edible fruit or leaves with quassia, as it imparts a bitter taste not 

 easily got rid of. According to the Jamaica Bulletin, nothing 

 has been so successful in driving black-ants away as Bitterwood 

 solution. 



Resin or Rosin. This enters into the composition of several 

 valuable spray-fluids which destroy different forms of scale-insects, 

 being especially suited to deciduous trees. It acts by depositing a 

 covering over the insect, thus killing the latter by preventing its 

 breathing. The following formula is recommended : Resin, 4 Ib. ; 

 fresh oil (seal or train oil), 2 pints; caustic soda, l| Ib.; water, 

 10 gallons. Boil the first 3 ingredients mixed with the water until 

 the resin is dissolved, then make up to 15 gallons of water. 

 Before using the solution it should be diluted with nine times its 

 quantity of clear water. This solution is recommendecl in America 

 for use against the "sooty-mould" on Orange and other Citrus 

 trees. 



Tobacco juice. An efficacious insecticide (also a fungicide) 

 for aphides, used largely in Europe, America, etc., more particu- 

 larly in plant-houses. The juice when of the standard strength is 

 diluted with 100 parts of water for spraying purposes. The plants 

 should be sprayed after sunset, and syringed with clear water on 

 the following morning. The juice may be prepared by soaking 

 i Ib. common tobacco leaf to a gallon of hot water. 



Tobacco-smoke is chiefly used for fumigating plants in glass- 

 houses, being a powerful insecticide for certain insects. It is 

 obtained by burning tobacco, or paper steeped in tobacco juice. 

 More effective, however, than tobacco-smoke, and less harmful to 

 tender plants, is the vapour caused by the heating of the newer 

 Nicotine Vaporisers, such as the "XL. All Vaporiser" and 



