CATCHING BUTTEBFLIES AND MOTHS 71 



leaves exuding through the rag and spoiling the insects' wings. 

 But if the reader should prefer to try this on account of its simpli- 

 city, it will probably occur to him that a bottle may be used instead 

 of a tin box. 



A well-made laurel box, with a fixed metal partition, is a piece 

 of apparatus strongly to be recommended to all young entomo- 

 logists who desire to test the relative value of the various poisons 

 that are used by the different experts ; for with it any one of these 

 substances can be used. In the poison compartment you can place 

 pieces of ' cyanide ' wrapped in blotting paper, or any kind of 

 porous substance moistened with liquid ammonia, chloroform, 

 benzole, or any other volatile liquid insecticide. All the above- 

 named substances are declared to be ' the best,' so they must all 

 be worth the trial. 



' Cyanide ' is valued on account of its lasting powers. A cyanide 

 bottle well charged will retain its efficiency throughout a whole 

 season. I always recharge two in the spring, one for active service 

 in the field and the other as a reserve force ; and these kept in a 

 cool place do good execution throughout the year. If they should 

 exhibit a slight failing, a few minutes' warming before a fire will 

 improve them ; but for field work it is better to recharge. At 

 the same time see that the corks are in good condition. 



Next to the ' cyanide,' the bruised laurel takes the first rank for 

 permanency ; but you must not expect this to last many days. 

 For a few days' continuous work one charge will suffice, but if the 

 laurel box has not been in use for some time you must have a fresh 

 supply. 



The liquid poisons, such as ammonia, chloroform, and benzole, 

 are so volatile that they are very powerful for a short time, but so 

 much vapour is lost each time the box is opened that it is absolutely 

 necessary to carry a bottle of the one you use into the field with 

 you. Also see that you have sufficient of the blotting paper or 

 other absorbent to prevent the liquid from leaking through the 

 perforations of the partition. 



If you choose ammonia a substance that is not regarded as a 

 poison, and is therefore easily obtained from any chemist always 

 get the strongest, and see that it is labelled ' Liq. Ammonia, S.G. 

 *880 ' as a guarantee. A small bottle such as you can conveniently 

 carry in the waistcoat pocket will contain sufficient for a day's 

 work. Use only a few drops at a time, but renew frequently. 

 Although the ammonia corrodes cork yet a good cork is far prefer- 



