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 drams of the cyanide in a little water, using a gla.s.s 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, without 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.
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 b.u.t.terflies immediately.
[Ill.u.s.tration: FIG. 44.--SECTION OF THE LAUREL BOX.
_a_, s.p.a.ce for insects; _b_, perforated part.i.tion; _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 part.i.tion may be used, fixed with a few brads, driven into it from the outside. With the fixed part.i.tion, 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 part.i.tion 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 leaves exuding through the rag and spoiling the insects" wings. But if the reader should prefer to try this on account of its simplicity, 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 part.i.tion, is a piece of apparatus strongly to be recommended to all young entomologists 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 part.i.tion.
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 preferable for the pocket to a gla.s.s stopper, for its elasticity prevents it from losing its hold, and the liquid from saturating your pocket and its surroundings; but a gla.s.s stopper is certainly better for the stock solution kept at home.
Most of the above remarks apply equally well to benzole and to chloroform, but the latter is so powerful a poison that a very little is required for a day"s work, and consequently a very small bottle is more convenient. The dealers in naturalist"s appliances supply metal "chloroform bottles" with screw stoppers and a small nozzle that will allow the liquid to run out only in drops. This is a very good arrangement, since it enables you to avoid the "drop too much" which is not only unnecessary and therefore wasteful, but saves you from experiencing the disappointment of an empty bottle before your work is half done.
[Ill.u.s.tration: FIG. 45.--THE CHLOROFORM BOTTLE.]
Some entomologists recommend the solid carbonate of ammonium instead of liquid ammonia, but this is not so powerful. It must be remembered that we have the b.u.t.terflies to consider, as well as our own convenience, in the selection of the poisons we use. It is the opinion of many well-known entomologists that "insects cannot feel pain," and that we are therefore at liberty to deal with them in any way we please. Still it is as well to save all possible suffering, and be satisfied with no killing box that is not practically instantaneous in its effects.
Among other poisons used by entomologists I may mention sulphur fumes and tobacco smoke. The former may be obtained by burning a little sulphur or a sulphured lucifer match under the perforations of a killing box of the pattern described, and the latter--well, every smoker knows that. I should at once condemn the former method, at least for field work, as troublesome and inconvenient; and as to the other, I have tried the effect of a puff (and many puffs) of tobacco smoke on an imprisoned insect, but was so dissatisfied with the result that I am not likely to do so again.
We have now considered a good many insecticides more or less suitable to our purpose, but there still remains the unsolved problem as to which is the best. Each one has its advantages. For _convenience_ nothing beats the cyanide bottle. It is very speedy in its action, and the use of a bottle is a little preferable to a metal box, for you can always satisfy yourself as to its efficiency without opening it. Cyanide, chloroform, benzole, and some others render the insects more or less brittle and stiff, so that it is not so easy to "set" them for the cabinet. Perhaps, if you happen to have a supply of growing laurel close at hand, you cannot do better than stick to the laurel box. The time taken in bruising up a few leaves is inconsiderable, and the moisture given off from them will keep your insects moist and supple, or will even "relax"
them if they have become rigid. But try various plans for yourself, and you will be able to settle a question which all the entomologists in the world cannot answer for you--which method answers best in _your_ hands.
The next item for our consideration is the "collecting box." This is merely a box in which the b.u.t.terflies are pinned as soon as they are dead. Here, again, we shall note a few variations from which a selection can be made according to the means or the ingenuity of the reader. For a couple of shillings you can obtain a good zinc collecting box, lined with cork, of oval form (a most convenient shape for the pocket), and quite large enough for one day"s captures; and half that modest sum will purchase a wooden box, also lined with cork, adapted to the same purpose.
As with many other things, so with collecting boxes, the cheapest is often the dearest in the end. You may feel inclined to save a shilling by buying a wooden box, but you are sure to discard it after a little practical experience for a metal one. We shall speak a little later on concerning the advisability of "setting" the b.u.t.terflies as soon as possible after capture; but this is not always practicable, especially after a good day"s catch. Now, if the insects are pinned in a wooden box, they soon become dry and rigid, and consequently cannot be "set"
till they have been put through the more or less tedious process of "relaxing." If you use a wooden collecting box you will often find, on a hot and dry day, that all or nearly all your b.u.t.terflies are rigid before you arrive home; but a metal box will keep them moist and supple, so that you can even put off the setting till the following day if you are unable to do it immediately after your return.
Another point worth considering is the best economy of s.p.a.ce. If your collecting box is only about one inch deep inside, you have room for only one layer of pinned insects; but a box only a little deeper may be lined with cork both at top and bottom, and thus be made to accommodate double the number. The zinc boxes sold by the dealers are generally lined with cork in this manner, and are, of course, deep enough for the double layer of specimens; but the wooden boxes are sometimes lined on the bottom only. After these few remarks you will at once see the economy of expending the extra shilling on the former.
Although the prices of collecting boxes are low, yet there are many who would prefer making their own, and there is much to be said in favour of this. A great deal of pleasure is to be derived from the construction of your own apparatus, especially when that apparatus is afterwards to be used in the pursuit of a delightful hobby. During the whole of the time thus engaged, you are looking forward with the most pleasurable feelings to the glorious treat before you, and every joint you make seems to bring you nearer to the realisation of your joys. During the bleak winter months there is no better employment for an entomologist who has a little spare time than the preparation for the next outing. It is just one of those artful schemes by which he seeks to get as much pleasure out of life as it is capable of affording. How many there are who, for the lack of a pleasant and instructive hobby, find their leisure hours the most dismal of all, and who complain of the toil and wearisomeness of their lot! The mournful thought with them is, "Is life worth living?"
but who ever heard such an expression from the lips of an active entomologist?
But I must have done with moralising and proceed to business. The question is--How shall we set to work about the construction of a collecting box? If it is to be a wooden one, select or make a box of such a size as to suit your pocket or satchel, and cover the bottom, and lid too if the depth allows of it, with sheet cork or slices of good wine corks, about one-eighth of an inch thick, fixed on with glue.
The metal box is not quite so easy, but even here you may save yourself much work by keeping your eyes open. Very neat little collecting boxes can be made out of the flat metal boxes in which are sold certain favourite brands of tobacco. Some of these are just the right depth, and also of a very convenient size for the coat pocket. Beg one of these boxes from a smoking friend, and if the lid is not held by a hinge (a great advantage, by the way), you can easily solder on a bra.s.s one.
All that remains now is the fixing of the cork. Buy a sheet of cork at a naturalist"s shop, this being a commodity always in stock, and cut out two pieces just the size to cover the bottom and the lid.
Gum and glue are not very satisfactory as fixing agents, for, as you will presently learn, there are times when it will be necessary to keep the box moist, and moisture softens both these substances. The cork must be fixed by means of little strips of metal. Here are two ways of doing this:
First.--Cut a few little strips of sheet tin, each about two inches long and one-eighth wide. Double and bend them as shown in fig. 46, and solder them to the surfaces which the cork is to cover (fig. 47). As the cork is pushed in its place, these little slips are allowed to force themselves through slits in it made by means of a penknife, and then the ends are bent over as shown in fig. 48. Two or three such fasteners will be quite sufficient to hold down each sheet of cork.
[Ill.u.s.tration: FIG. 46.]
[Ill.u.s.tration: FIG. 47.]
[Ill.u.s.tration: FIG. 48.]
[Ill.u.s.tration: FIG. 49.]
Second.--Put the sheets of cork in their places _first_, then make a few little slits through both metal and cork with the point of a penknife, and then bind the two together with a few ordinary paper fasteners. This arrangement is shown in section in fig. 49.
Just one point more concerning the metal collecting box. You will often call moisture to your aid in keeping the b.u.t.terflies flexible and soft.
This will have but little action on zinc, but will sooner or later cause the "tin" (really tinned iron) box to rust. Here, then, is a point in favour of zinc, but still a home-made "tin" collector will last a long time if kept dry when not in use.
As already hinted, there are times when it is desirable to take home certain b.u.t.terflies alive, either for a study of their movements or for the purpose of securing eggs for breeding. To this end you must provide yourself either with a number of "chip boxes" with a few small holes p.r.i.c.ked in the cover, or with some metal boxes with perforations for the admission of air. If the latter, you will have no difficulty in securing a few "tin" boxes of suitable size, but, as the surface of the metal is very smooth, you should always introduce a few leaves or something else that will provide a foothold for the inmates.
The last item of the outfit is the pins. Ordinary draper"s pins are quite out of the question. They are far too thick and clumsy for the collector"s work. If you are not already acquainted with the "entomological pins," you had better ask a dealer to give you a sample card. This will be very useful for reference until you become well acquainted with the various lengths, thicknesses, numbers and prices.
The card will contain one of each kind, with price and number attached.
If you fix a b.u.t.terfly with the ordinary pin, you may find the latter partly covered over with verdigris after a time. This bright green substance is formed by the action of decomposing animal matter on the copper of the pin, and gives a very unsightly appearance to the specimen. To avoid this the entomological pins are either silvered, blackened or gilded. The silvered pins tarnish after a time, but the two other kinds keep their colour well, and are therefore better. The gilded ones are rather expensive and unnecessary, and perhaps the black ones are to be preferred to the silvered, although they are rather more costly.
Most dealers will supply you with a box of mixed pins, each box containing about six different sizes. This is very convenient for those who work in a rather small way; but if you intend to make entomology a prolonged study you had better get an ounce or so of each of the more useful sizes.
b.u.t.terflies vary much in size, and Nos. 3 to 8 are the most useful sizes of pins to fix them; No. 3 being for the largest, and 8 for the smallest.
Supposing all the foregoing requisites to be quite ready, still you are really by no means prepared for all your work. The b.u.t.terflies captured should be set as soon as possible after your return, and everything required for _this_ part of the work must be in perfect trim. Yet I think it will be more convenient just now to confine our attention to the subject of "Catching b.u.t.terflies," leaving all the indoor work to form the substance of another chapter. Our next point, then, shall be the consideration of seasons, times, and localities.
The earliest of the b.u.t.terflies make their appearance on the wing in April, or, if the weather is mild, towards the end of March; and from this time you can find employment up to the end of September or the beginning of October--a period of about seven months. But it must not be supposed that all parts of this long season are equally prolific, and will yield equally valuable catches. Remember the short term of a b.u.t.terfly"s life, and bear in mind that each one has its own regular season in which to spend the winged state; you will then see that anyone who wishes to "work" as many species as possible must arrange his outings in accordance with the insects" own times.
Some b.u.t.terflies are double-brooded, and the two broods may not come forth at certain fixed times. Hence they seem to be on the wing almost without cessation for several months together, and therefore need not have a special day set apart for them. But others are more uniform in their date of appearance, and die off at about the same time. To catch such as these you must be careful to watch the weather, make allowance for any severities that may tend to cause a delay, or an unusually high temperature that may hasten their emergence, and then select a day in which you may expect to find them fresh and unworn. A week too early, and none are to be seen; a week too late, and nearly all you catch are worn and worthless.
A glance at our Calendar (Appendix II) will give you a few ill.u.s.trations in point. Thus you will observe that May is a month for the "Whites,"
early "Blues" and certain of the Fritillaries; July for most of the Hairstreaks and Browns, and so on. Before you have been long collecting you will have captured the very common species, and then you will find that your b.u.t.terfly hunts are very unproductive unless you make it a point to try for certain species at the proper times.
Time, however, is not the only thing to take into account when preparing for a day with the b.u.t.terflies. It is equally important that we should carefully select our locality in accordance with the known haunts of the various species. As long as you are simply working up the common kinds, you may wander almost at random in waste places, flowery meadows, corn fields, railway banks, &c.; but when you have secured a few specimens of each of these, you must search out the favoured resorts of the more local and the rarer species. For instance, wooded spots must be visited if you are to take certain of the Fritillaries, oak woods for the Purple Emperor and the Purple Hairstreak, fenny districts for the beautiful Swallow-tail, and so forth. In some cases the b.u.t.terflies are closely restricted to certain isolated localities, to which you must travel if determined to obtain them.
There yet remains another important matter to consider, and that is the kind of day you shall select for your outing. b.u.t.terflies are not only strictly day-fliers, but most of them venture out only on bright days.
Always choose as hot a day as possible, with a very bright sun. If you are to be out for a full day"s collecting, manage to be on the hunting ground at about ten o"clock in the morning. As a rule there are not many out before this time, and some do not appear to stir till an hour later: still there are a few "early birds" among them, one of which--the Wall b.u.t.terfly--I have seen on the wing before eight.