CATALOGUE OF INSECTS. 29 



When the cubic contents of a house or box are ascertained, weigh 

 out the cyanide in paper bags in small lumps for a day's use, and 

 keep dry. Water and acid are measured out as required. The fumi- 

 gating jar should be of glazed earthenware or glass, and should hold 

 twice as much as is needed, to avoid spilling or sputtering over. 

 When all is ready measure ont Jirst the water ; then the acid, which 

 should be poured into the water slowly. The acid is very corrosive, 

 and must be carefully used ; it heats when added to water, and boils 

 violently when water in small quantity is added to it ; hence, the 

 water should never be poured into the acid. When everything else 

 is ready, drop the bag of cyanide into the diluted acid, and either 

 shove in the slide or close the doors at once. It requires a few mo- 

 ments for the acid to eat through the paper bag, and this gives ample 

 time for the operator to get out if the jar is loaded inside. Fumiga- 

 tion should continue at least two hours, and may continue safely all 

 night. The fumigating house on the Village Nurseries at Hights- 

 town is arranged so that a wagon-load of stock may be backed into 

 it, and the stock fumigated without unloading. When the house is 

 opened it should be allowed to ventilate at least ten minutes, door and 

 window being both opened to facilitate the escape of gas, before it is 

 entered. This fumigation will kill all plant lice and scale insects in 

 any except the egg stage, unless they are protected by some acci- 

 dental covering. No method can be entirely perfect, and a scale, or 

 even a group of scales, may be so covered by a leaf, a spider-web or 

 a cocoon that the gas does not reach it. Yet these instances will be 

 rare, and the process is as nearly perfect as anything we have. 



It will be noted that our insecticide battery is not on the whole a 

 very large one, yet it is sufficient when intelligence is used in their 

 application. There is an abundance of secret or patented insecticides 

 at high prices, but these are best avoided as a rule. This caution 

 does not apply to simple products like fish-oil soap, tobacco extracts 

 or the like, which are often more cheaply purchased than made, but 

 to products with fancy names which give no indication of the killing 

 agent, like "Black death," "Kill M right," &c, all of which may 

 be good, but are likely to be otherwise. 



Preventive methods have not been touched upon, since they vary 

 with almost every species against which they are used. 



Finally, I do not mean to suggest that no materials other than 

 those mentioned are useful for insecticide purposes, but the range of 

 such substances is usually limited and their discussion would carry 

 this chapter beyond all reasonable bounds. 



