CATALOGUE OF INSECTS. 27 



which the slaked lime and salt are added to the sulphide of lime 

 already obtained and boiled an hour longer, the whole being then 

 diluted with water to make ioo gallons. It must be strained before 

 application. 



There are local variations in the preparation of this mixture, but 

 the product is always a double sulphide of lime when the process has 

 been thorough. 



Caustic potash and caustic soda are much used as a winter wash on 

 fruit trees and keep the trunks bright and clear of lichens, fungous 

 growths, scales and other pests that would ordinarily winter in such 

 places. One pound in one or two gallons of water is a usual strength, 

 but must not be employed on foliage or active plant tissue. 



Hot or very cold water may be sometimes used to advantage ; but 

 their range is exceedingly limited, and usually some other substance 

 is more satisfactory and actually less expensive. 



Sulphur has also a limited range, and is practically useless in the 

 field as an insecticide ; but in the greenhouse, where mites or red 

 spiders are troublesome, it can be made very useful. Crushed or 

 powdered sulphur in considerable quantity in a barrel of water may 

 be stirred from time to time for weeks or months, and the sulphur 

 water so formed may be used on the plants ; or flour of sulphur may 

 be dusted on the ground or on the pipes so as to vaporize slowly. 



Naphthaline is another substance more useful in protecting stored 

 products indoors than for destroying field pests ; but it is excellent 

 to keep " moths " from clothing and gnawing pests out of the wheat 

 bin. It is a petroleum product, has a low melting point and ignites 

 readily — a fact which should be kept in mind. 



Bisulphide of carbon is a volatile liquid of vile odor, giving off fumes 

 exceedingly poisonous to insect life, and it may be used in some cases 

 to destroy insects in granaries or other moderately tight receptacles. 

 The vapor is heavy and sinks; hence the material should be placed on 

 top of the mass of grain to be cleared. Roughty, it requires a teaspoon- 

 ful of liquid to fill one cubic foot of space with vapor, and seed grain 

 may be exposed for 24 hours without danger to its germinating 

 quality. In field practice the bisulphide is useful against the melon 

 louse when it first appears and only isolated hills are affected. These 

 can be covered with any sort of tight cover and a proper amount of 

 the insecticide placed in a small dish — a clam shell will answer — the 

 cover being kept on an hour at least. All hills so treated are thor- 

 oughly cleared and spread throughout the field may be so prevented. 

 Ordinary bisulphide of carbon is expensive, but a "Fuma" bisul- 

 phide is made by Edward R. Taylor, Cincinnati, Ohio, which may 

 be obtained at a satisfactory rate for insecticide purposes. 



