84 INSECTICIDES AND SPRAYING. 



latter from rain and helps it to remain on the plant. The wash has of 

 itself no poisoning effect on cattle or other animals, and may be safely 

 applied at all times. It has also no effect as a stomach poison against cater- 

 pillars, etc., and is intended simply as an efficient contact poison against 

 all small sucking insects except the mealy ones. 



Tobacco. 



Fermented tobacco forms a decoction which acts as a mild stomach 

 poison and also as a contact poison. It requires to be soaked in water to 

 extract the alkaloids and then is best used with the addition of soap. 

 It is a weak insecticide, valuable against plant lice, mealy bugs, soft 

 sucking insects and very small caterpillars, but not so effective as any of 

 the above mixtures. It is obtainable in many parts of India, and the wash 

 is best prepared from the stalks and refuse of the leaf tobacco. 



Sanitary fluid. 



The liquids called by this general name consist largely of creosote 

 oil containing carbolic acid (phenyl). Mixed with water they emulsify, 

 owing to the presence of rosin soap, and in weak emulsion are excellent 

 contact poisons. This is an insecticide not in general use elsewhere 

 but which has given excellent results in India. A strength of one 

 in one hundred of water is excellent against all forms of soft sucking 

 insects, against plant lice, mealy bug, green bug, etc. At a strength of 

 one in sixty of water, it is a powerful insecticide, which kills all but 

 the most resistant sucking insects and has a considerable effect on cater- 

 pillars, small grasshoppers, etc. At greater strength it burns the 

 foliage of actively growing plants ; it was used at one in forty against 

 the Bombay locust, killing a large percentage, and at one in twenty 

 killing everyone sprayed, without injury to the hardy foliage of forest 

 trees. 



Other contact poisons. 



Countless mixtures have been used as contact poisons since these 

 were first tested and a great variety are still in use. In India only 

 what are known in Europe as " summer washes" can be used, which 

 restricts the available number. There is sufficient latitude in the above 

 mixtures to suit every case and no good will be done by discussing the 

 hundreds of mixtures recommended. This applies also to the patent 

 insecticides ; none are yet proved to be as good as the insecticides made 

 pn the spot and none have the combined efficiency and usefulness of crude 



