CATCHING BUTTERFLIES AND MOTHS 69 



cyanide, see that the bottle is kept quite out of the reach of the 

 inquisitive and sugar-loving juveniles of the house. 



The quantity above mentioned is more than you will require for 

 the first ' charge,' but you will soon experience the convenience of 

 having a supply always at hand for recharging when your cyanide 

 bottle fails to do its work expeditiously, or when an accident calls 

 for the somewhat sudden appearance of a new one. 



Now procure a bottle for your work. Its mouth must be wide 

 enough to take the largest insect you hope to catch, and the widest 

 part of the bottle need not be much larger. Get a perfectly sound 

 cork to fit it tightly ; and, to insure the more perfect exclusion of 

 air, paint over the top of the cork with melted paraffin wax. 



Dissolve a few drains of the cyanide in a little water, using a 

 glass rod to stir up the mixture till the solid has all disappeared ; 

 and be careful that neither the solid nor the solution touches 

 the skin if it should be in the slightest degree scratched or 

 broken. Now sprinkle plaster of Paris into the solution, a little 

 at a time, and stir all the while. As soon as the mixture begins 

 to set, pour it into your bottle as cleanly as you can that is, with- 

 out touching the sides and press it down with the flat end of a 

 stick if it is not level. Now cork it, and put the bottle away in a 

 cool place till required for use. 



This is, I think, the best way of charging the bottle ; but there 

 are two other common methods that may, perhaps, be regarded as a 

 little more simple. One is this : put a few small lumps of the 

 ' cyanide ' into your bottle, and then cover them with a stiff mixture 

 of plaster of Paris and water, and press down as before. The- other 

 plan is to cover the ' cyanide ' with a few thicknesses of blotting 

 paper, cut just a little larger than the inside of the bottle. The first 

 of these two methods is fairly satisfactory, but I have always found 

 that the charge, when made in this way, has a tendency to become 

 wet and pasty, in which condition it will spoil the wings of the 

 insects. The other is very objectionable, especially for field work, 

 for the blotting paper fails to keep its place while you are on the 

 chase. If the plaster is used, the mixing must be done quickly and 

 without hesitation, or the mixture will become solid before you can 

 press it into your bottle. 



We will not enter now into the pros and cons of the cyanide 

 bottle, but will consider the advantages and disadvantages of the 

 various methods of killing the insects after we have noticed a few 

 more. 



