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.
The 'laurel box' has had many devoted advocates, although it does not seem to be much in use now. It is a very good arrangement, however, but is a little more troublesome than the cyanide bottle, as it requires frequent replenishing.
A very good laurel box may be prepared as follows. Get a small tin box of cylindrical form, measuring about five inches by two, and cut a circle of perforated zinc or wood just the size to fit it snugly as a false bottom without any danger of falling out of its place. Now gather some of the young leaves of the green laurel bush, and beat them almost to a pulp with a mallet or hammer. Place this in your tin box, and press down the perforated false bottom on it. The bruised laurel leaves give off a very powerful odour, which stupefies butterflies immediately.
Fig. 44.—Section of the Laurel Box.
a, space for insects; b, perforated partition; c, bruised laurel leaves.
Of course the reader may be able to think of various other ways in which the laurel box may be made. Any arrangement will do providing the vapour can come to the insects without allowing the leaves to touch their wings; and any ingenious youth could manufacture a more satisfactory article than the one I have mentioned. My desire is, as far as possible, to give instructions that may easily be carried out by anyone, even if he has not the slightest mechanical skill, leaving the clever youth, sometimes, the opportunity of displaying his own inventive power. But in this case I will give a few suggestions concerning other ways in which a laurel killer may be constructed. A firm and fixed false bottom is a decided advantage. This is easily managed by fixing a circular piece of perforated zinc or 'tin' by means of a little solder; or even a wood partition may be used, fixed with a few brads, driven into it from the outside. With the fixed partition, however, you must have a lid at each end of the box. This is easily managed if you get two tins of the same size, knock out the bottom of one, and fit the lid of the other in its place.
I have heard of laurel boxes without any partition save a piece of rag in which the bruised leaves are wrapped. The whole is pressed into the box so firmly that it is not likely to be displaced while you are on the chase. I do not recommend this, for in addition to the chance of its slipping there is a danger of the sap of the