Читать книгу The Butterflies of the British Isles - Richard South - Страница 12

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Fig. 12.

Y-piece

Naturally the first matter for consideration, when the formation of a collection of butterflies has been decided upon, is how to set about it. Well, there are two methods of effecting our purpose. The specimens may be purchased from a dealer in such things, or we may acquire an outfit comprising net, boxes, and pins, and go in search of the insects ourselves. Apart from its healthful and entertaining possibilities, the latter method has very much to recommend it. In the first place, those who are at all observant—and no true lover of Nature can be suspected of being otherwise—will become acquainted with the objects under natural conditions, and so be enabled to appreciate them more highly than could be the case if they were obtained in any other way. The chief purpose in making a collection of Natural History specimens should be study of some kind rather than mere accumulation.

Nets.

The net may be a simple cane ring one of home construction, or the more elaborate, but not necessarily more efficient, fabrication of steel-jointed ring with grenadine bag and telescopic handle. A good serviceable butterfly-net may be fitted up as follows. Procure a light flexible cane, about 3 feet or so in length. Next, a Y-shaped holder (Fig. 12) for the two ends of the cane will have to be made, and either tin or brass may be used for the purpose. The latter is the better metal, and the parts should be brazed and not soldered together. (If difficulty is experienced in the manufacture of this article, it may be obtained from any dealer in entomological requisites for a few pence.) The bag may be made of leno, tarletan, or fine mosquito netting; the latter is the most serviceable, and should be used wherever it can be obtained. The size of the bag at the top, where it has a wide band to take the cane, should not exceed the circumference of the cane ring when fitted in the two arms of the Y-piece; the depth should be just a little less than the length of one's arm, and the bottom should be rounded off so that no corners are available for the butterflies to get into and damage their wings. An opening about 3 inches in length is left in the seam of the bag just under the Y-piece, so that the cane may be removed and rolled up when the net is put out of action. The ring band should be covered with some stouter material to prevent it from fraying, thin leather is sometimes used for this purpose; the slit in the seam also requires protecting on each side, and strengthening at the lower end by a crosspiece. An ordinary walking-stick, with the ferrule end thrust into the longer tube of the Y, will serve as a handle to the complete net.

Fig. 13.

Kite or Balloon Net.

The dealers adverted to above generally stock a variety of nets ready fitted for use. Among these is a very useful pattern known as the kite or balloon net (Fig. 13). This is made in two sizes, and as the writer has used this kind of net for at least twenty years, he is able to speak well of its merits. It does not need a stick for ordinary work, and the long end of the socket should be about 9 inches in length.

The "ring" being made of four separate rods, in addition to the Y-piece, some care will have to be taken when a balloon net is unshipped. It will be found a good plan to leave the two short curved canes in the hem or band of the bag, remove the two straight arms from the Y-piece and the band, place these on top of the bag when folded, and then roll all up together. A canvas or linen pouch or pocket, opening at one end, may be made to contain the whole affair.

The umbrella-net, when in its case, looks very like the familiar "gamp." Its chief merit is that it is quickly put up for use, and its principal defect is that the stick, which crosses the mouth of the bag, frequently damages the quarry.

Another implement of the chase known as the "Ortner" net is used pretty extensively on the Continent. English entomologists who have used it speak of it most favourably. Its great advantage over other nets is found in the simple and rapid method of its adjustment for use.

In connection with nets it may be well to advise the wielder to remember that carrying a threaded needle is a useful practice. Tears and rents are apt to occur, and it is well to have the means of repair handy.

Killing.

Some collectors seem to be expert at killing butterflies by pressing the sides of the thorax together. The method is not, however, as satisfactory as one could wish, and so no more need be said about it. For the happy despatch of insects, the cyanide bottle is frequently used. All that has to be done is to clap the open bottle over the captive while still in the net, then draw the gauze or what-not over the mouth of the bottle until the bung can be inserted, and the whole affair withdrawn from the net.

Cyanide of potassium is a deadly poison, and no inexperienced person should attempt to charge a cyanide bottle himself. In fact, chemists are not permitted to supply the poison to unknown customers. Under certain conditions, however, a chemist might consent to make up a killing bottle, and the following instructions may help him in doing this. A fairly strong, clear glass bottle, holding about 4 to 6 ounces; the mouth must be pretty wide, and closed with a well-fitting bung that has been dipped in melted wax; if the bung is of fine grained cork, the wax will not be needed. At the bottom of the bottle place a thick layer of the cyanide, and over this pour plaster of Paris which has been mixed with water and converted into a cream-like paste: one-third of the depth of the bottle to be occupied by the poison and plaster, but only a thin layer of the latter should cover the former.

Dealers who supply cyanide bottles (uncharged) also have in stock a brass bottle for chloroform, which some people prefer as a killing agent because it does not change the colour of insects as cyanide is occasionally apt to do. In using this, the insect should be boxed, then a drop of the chloroform may be allowed to run from the bottle over the perforated lid or bottom of the box, and a finger put over the hole or holes for a short time.

The majority of butterflies, if transferred to pill boxes from the net, settle down quietly. In this way they may be taken to one's home and there placed, boxes and all, into the ammonia jar, a simple but very effective contrivance. To start one of these lethal chambers, procure a good sized pickle jar, one of the brown earthenware kind, holding about 2 gallons. At the bottom put in several layers of stout blotting-paper, and have ready a covering for the mouth of the jar. This covering may be of skin, waterproof-apron material, or even thick brown paper. Before turning the boxes into the jar, lift up the blotting-paper, drop in about half a teaspoonful of strong liquid ammonia (⋅880) and replace blotting-paper. Directly the boxes are in the jar, put on cover and tie it down securely. If brown paper is used, a piece of pasteboard should be put over it and a weight on top of that. Suffocation takes place directly the gas reaches the insect, but it often happens that one or more of the boxes exclude the gas longer than others. At the end of half an hour all may be removed, but the insects will not hurt in any way if left in all night.

The best kind of boxes for field work are those known as "glass bottomed," as in these the captives can be examined and, if not wanted, may be set free. It is always better to retain only those specimens that we know are really useful, rather than to incur the necessity of throwing away insects after we have deprived them of life.

Pinning.

If butterflies are pinned on the spot, a collecting box will be required, and the most useful and convenient is one of an oval shape. This should be made of zinc, and lined with cork that is held in place by zinc clips. The cork should be kept damp when in use, and the water used for damping should have a few drops of carbolic acid mixed with it so as to prevent the formation of mould. Insects may remain in such a box for several days without injury. This box will also be useful for relaxing specimens that have been badly set, or have been simply pinned during the busy season.

In the matter of pins, it is not altogether easy to make suggestions. There are, perhaps, only two makers in this country of entomological pins, and each of these supplies a large number of sizes. The selection of suitable pins will largely depend on the method of setting adopted. Black pins are, however, the best for butterflies, and are now used almost exclusively.

In pinning a specimen care should be taken that the pin passes in a direct line through the centre of the thorax. Insects that are properly pinned set better, and have a neat appearance when arranged in the collection. For regulating the height of specimens on the pin, a handy graduated stage has been devised by Dr. Scarancke (see Fig. 14). Each of the little rests are hollowed to receive the body of the insect, so suppose we wish a quarter of an inch of the pin to show below the body of a specimen, the pin is pushed through a perforation in the centre of the rest groove marked "3/16" until the point touches the wooden base, and we have the required length.

Beginners would, perhaps, find three sizes of pins quite sufficient for almost every purpose—say, Nos. 10, 8, and 5 of one maker; or Nos. 9, 17, and 5 of the other. In each case the first size pin would be suitable for small butterflies, the second size for all other butterflies except quite the largest, for which No. 5 would remain. English pins are sold by the ounce.

Fig. 14.

Pinning Stage.

Setting.

Setting, as it is called, that is, spreading out and fixing the wings so that all their parts are displayed, arranging the horns, etc., is perhaps the most tedious work that the collector will be called upon to perform. The various methods will be referred to, and he must then decide as to which he will adopt. Each style may possibly be found to have its difficulties at first; but time and patience will overcome these, therefore he must be prepared for a good deal of troublesome practice before he quite gets "the hang of the thing," and can set out his specimens without removing a greater or lesser number of the scales.

Fig. 15.

Board for Flat-setting.

First, as to the flat and high setting as practised by almost every lepidopterist abroad and by some in our own country. Boards of the pattern, shown in the illustration, will be required; also some tracing cloth, and a pair of entomological forceps, bead-headed pins, etc. In these boards, it will be noticed, the sides tilt outwards; this is to allow for drooping of the wings, which generally occurs after insects are removed from the "sets." In this case the wings would settle dead flat, which is considered to be the acme of perfection in this style of setting. Carlsbad or other foreign pins would be used for this kind of work. They are of a uniform length, about one inch and a half, but vary in thickness, and are usually sold by the 100 or 1000.

Fig. 16. Fig. 17.

Longitudinal Section of Setting-board.Setting-board in use.

Manipulation of the specimen on these boards is as follows. Having carefully pinned it, leaving the greater length of pin below the insect, guide the pin carefully through the narrow opening (a Fig. 15 and the cork (Fig. 16) below to a suitable depth, so that the body of the insect rests in the groove and the wings lie easily on the board. Then take two strips of tracing cloth, glazed side downwards, and pin them on at the end of each side of the setting-board (Fig. 17). The strip should be just wide enough to cover all but the basal part of the wings. Now pass the strips over the wings, press one side lightly with the fingers of the left hand while the wings are moved into position with the setting needle (a fine needle with eye end fixed into the stick of a small penholder will do for this) from the uncovered base, a pin being inserted below the fore wing while the hind wing is brought into position, but when this has been done and another pin inserted to keep it in place, as shown in the diagram, the first pin may be removed; repeat the same operation on the other side. Other pins will be required to keep the horns, etc., in place. In dealing with the next specimen the strips will have to be turned back while it is fixed into position, then proceed as before. An imaginary line following the inner margin of the fore wings and passing through the pin on the thorax is an excellent guide to uniformity in setting. The groove will prevent the pin leaning to either side, but care should be taken that it does not incline either forwards or backwards. The strip of tracing cloth may be used more than once, but the roughness of the pin holes should be removed by drawing the strip across the back of a knife.

Fig. 18.

"Saddle" Setting-board.

The setting-boards most frequently used in this country have sloping sides, and are known as saddles (Fig. 18). Where tracing cloth is used, the modus operandi is exactly similar to that just described, but small pins will do for pinning down the strips, as the saddles are made of cork, or cork carpet, instead of wood.

Fig. 19.

Setting-bristle.

The following method of setting butterflies on the English kind of "board" or saddle is frequently adopted. Select a suitable saddle, that is one that has the groove wide enough to take the body, and rather wider than the wings when expanded. A setting bristle will then be required. This is made, as shown in Fig. 19, by fixing a fairly long and stout bristle, or a very fine needle, or a thin length of quill, in a cube of cork; the cork cube has a stoutish and sharp-pointed pin pushed through it as indicated. Having placed the first insect on the saddle with its body comfortably resting in the groove and the wings flush with the surface, the setting bristle is then brought into action. The point of the pin is rested on the saddle directly in the rear of the hind wing, and the top of the bristle touching the saddle in advance of the front wing. Tilt the pin slightly forward until the bristle presses lightly on the central area of the wings, then with the setting needle push the wings into the required position, and at the same time drive pin of bristle into the saddle. After the wings have been secured by means of braces (triangular pieces of thin card or stout paper, with a pin through the base of the triangle), proceed in the same way with the other side. Finally, fix a brace to the tip and angle of each fore wing to keep them from turning up in drying, and a pin or two may be required for the horns if these are not in a good position. Instead of using braces, a strip of transparent paper may be pinned over the wings beyond the bristle, but in this case the bristle must be pressed across the wings at a point nearer their base than in the previous method (see lower figure in Fig. 20). In lieu of a setting bristle a length of sewing cotton may be used. Tie a double knot at one end, and through this pass the point of a pin in such a way that the cotton lies flush on the saddle when in use. Insert the pin firmly in the saddle a little in advance of the fore wing, then draw the cotton downwards across the wings and hold it taut, with the fore finger of the left hand placed on it just in rear of the hind wing. Whilst so held the wings can be got into pose with the setting needle, and braces may then be applied as previously directed.

Fig. 20.

Brace and Band Modes of setting.

Fig. 21 shows a specimen set by a method that is in vogue in the north. Blocks of soft pine, grooved and bevelled as in the cork saddle, are easily made. Down the centre of the groove there is a saw cut for the point of the pin to enter, and nicks are cut along the bottom edge at each end. One end of a length of cotton is knotted and fixed in a nick, then a turn is taken over the wings on one side; these are placed in position and secured by other turns of the cotton. The other side is then treated in the same manner, and the end of the cotton fastened off in one of the nicks. This is a quick and, in skilled hands, a very neat method.

As specimens after being set will have to remain on the setting boards or saddles for at least a fortnight, it will be necessary to protect them not only from dust, but from possible attack by ants, cockroaches, mice, etc. This is best ensured by placing the sets into a receptacle called a setting or drying house. Dealers supply these, but the young collector may have a knowledge of carpentry and could make one for himself. The height and depth of such a construction would depend upon the number and the width of the boards or saddles that would be put therein. The width would be that of the length of the boards, which is usually 14 inches. About a quarter of an inch of cork is cut off each end of the saddles, and grooves are cut in the sides of the house for these to run in. The back and the door should have a square of fine perforated zinc inserted in them for ventilation. As an example of holding capacity it may be well to note that a house with a height of 12 inches, and a depth of 6 inches, inside measurement, would take eighteen 2-inch boards if the grooves were cut at 2 inches apart, or twenty-four boards of same width if 1-1/2 inch only were allowed between the grooves.

Fig. 21.

Cotton Method of setting.

In taking insects off the sets, the braces or strips should be removed from the wings, and the pins from the horns, with care, as a good deal of damage can be done in the performance of this operation, simple as it seems to be. A little twist of a brace and away goes a patch of scales, a side slip of a pin and off comes a horn.

Pending the arrival of that twelve or twenty drawer cabinet, the beginner will probably be content to arrange his specimens in boxes. A handy sized box is one measuring 14 inches by 10 when closed, and it should have a cell for naphthaline.

Before putting the specimens away into boxes or drawers they should be labelled with the date of capture, the locality, the name of the captor, and any other detail of interest in connection with it. All these particulars may be written on small squares of paper and put on the pins under the specimens.

Cabinets or boxes containing insects should always stand where they are free from damp, otherwise mould may make its appearance on the specimens. Mouldy insects may be cleaned, but they never look nice afterwards; so it will be well to bear in mind that prevention is better than cure. Where drawers and boxes are not properly attended to in the matter of naphthaline, mites are apt to enter and cause injury to the specimens. If these pests should effect a lodgment, a little benzine poured on the bottom of box or drawer will quickly kill them. The benzine, if pure, will not make the least stain, and of course the drawer or box must be closed directly the benzine is put in. Do this only in the daytime.

Rearing butterflies from the egg is much practised, and is a very excellent way. One not only obtains specimens in fine condition, but gains knowledge of the early stages at the same time. The eggs of most of the Whites, the Orange-tip, the Brimstone, and some others are not difficult to obtain, but searching the food-plants for the eggs of many of the butterflies is tiresome work, and not altogether remunerative. Females may be watched when engaged in egg-laying, and having marked the spot, step in when she has left and rob the "nest." The best plan is to capture a few females and enclose them in roomy, wide-mouthed bottles, or a gauze cage, putting in with them a sprig or two of the food-plant placed in a holder containing water. The mouth of the bottle should be covered with gauze or leno, and a bit of moistened sugar put on the top outside. Either bottle or cage must be stood in the sunshine, but it must be remembered that the butterflies require plenty of air as well as sunshine, and that they can have too much of the latter.