Butterflies and Moths (British)

CHAPTER IX

SETTING AND PRESERVING

Up to the present we have been dealing only with living forms – learning how to catch and rear the Lepidoptera that fall to our lot; but now we have to become acquainted with the methods of preparing our dead specimens in such a way that they may form a useful collection for future study and reference. Our first attention shall be given to the apparatus necessary for this work.

The most important requirement is the setting boards, of which several are necessary, the sizes varying according to the dimensions of the different insects to be 'set.' The lengths of all the boards should be the same, not only for the convenience of packing when not in use, but also in order that they may, if required, be arranged neatly in the 'drying house' to be presently described. The widths only will vary, and in this respect the boards must be adapted to the measurements of the insects from tip to tip when the wings are fully expanded. Thus, a set of a dozen boards, ten or twelve inches long, and from one to five inches wide, will do for a good start. Of course you may commence with a smaller number than twelve, but if you really mean to do the thing well, you will eventually require a good stock of boards.

Here, again, it may be mentioned that all the necessary requisites may be purchased ready for use, a set of boards and a drying house complete costing from ten to twenty shillings according to size and quality; but as the reader, like myself, may prefer to construct his own, I will supply him with hints and suggestions sufficient for the work.

Each board is constructed in this way. Cut out and plane up a piece of wood of the required length and breadth, and about one-eighth of an inch thick. Glue on the top of this a layer of cork about half an inch in thickness, leaving the whole under a moderate pressure until the glue is quite hard. The sheets of cork for this purpose may be bought at any naturalist's stores; but slices cut from good large bottle corks may be made to answer equally well if you don't mind the extra time expended in cutting and fixing.

When the glue has well set, trim off the edges of the cork flush with the sides of the wood, and then cut out a groove down the whole length of the cork, of course in the middle, and of such a size that it will just contain the bodies of the insects for which it is intended.

Fig. 60. – Section of a Setting Board.

The satisfactory cutting of this groove is not a very easy matter, but if its position is first carefully marked, a long rat-tail file may be made to plough it out neatly and regularly. As an alternative the following plan is good. First cover the wood with a layer of cork about a quarter of an inch thick, and then glue on the top of this two narrower strips, about as thick as the bodies of the insects for which the board is intended, leaving a space of the required size between them, as shown in fig. 60. In this way you get a groove of square section, that is in some respects preferable to the round one cut out by means of the rat-tail file.

Fig. 61. – Sections of Setting Boards.

Now comes a question about which there is a difference in the tastes or fancies of entomologists. Shall the boards be perfectly flat on the top, or shall the sides slope from the groove, or shall the surface be rounded? A glance at the three sections of setting boards will show clearly what is meant. The rounded board is most commonly used, and the graceful curve thus given to a butterfly or moth set on such is certainly attractive; but it is not natural. The wings of these insects are rigid, and are never seen bent into such curves in a living specimen. For this reason I much prefer a perfectly plane surface on each side of the groove. Then, as to whether there shall be a slope or not, this is a matter of less importance. A very decided sloping of the wings is certainly not so convenient for future examination; nor does it, to my mind, look nearly so well as both sides in the same plane, or at a very gentle inclination. But perhaps this subject had better be left to the taste of the reader, remembering, however, that, whatever plan be adopted, all the boards should be alike in this respect, so that there may be a degree of uniformity in the cabinet.

The surface of the cork must, in all cases, be nicely smoothed down with glass paper, and then covered with thin white paper, fixed to its surface with ordinary paste.

When insects are on the boards, they should be placed in an airy spot, as free as possible from dust, while they are drying. Hence the advisability of some form of 'drying house.' This is simply a box, standing on end, and provided with a hinged door consisting of a sheet of perforated zinc in a wooden frame. The boards may slide in this on little slips of wood nailed or glued on to the sides, or the wooden bases of the boards may project beyond the cork at the ends, and slide into grooves in the side of the house.

Fig. 62. – A Butterfly on the Setting Board.

Beyond these requirements nothing is wanted save a good stock of pins, thin card or ordinary writing paper, and a 'setting needle.' The last-named item is simply a needle mounted in a handle, and a good one may be made by thrusting the head of a darning needle into a piece of twig. The pins used for setting – that is, for fixing the pieces of paper or card to keep the parts in position – may be of the ordinary kind; but entomological pins are far preferable, even for this purpose; for, being much thinner, they do not damage and disfigure the setting boards so much.

Now as to the setting. First see that the pin with which you are to fix your dead insect passes centrally through the thorax. Then fix it firmly on the setting board, its body lying neatly in the groove of the cork. Cut out some little pointed strips of card or paper, and, after bringing the wings into position with the setting needle, fix each one by a pinned strip. In spreading out the wings, care must be taken not to pierce them at all, but simply to push them into their place by pressing the needle at their bases, or by putting the needle beneath and lifting them out.

Instead of pointed pieces of card, uniform strips of paper may be used, as shown in fig. 63, each strip passing over both wings.

After the four wings have been properly arranged, a few extra pins may be used to keep other parts in position. Thus, the antennæ may be placed at equal angles, the proboscis may be extended, and a couple of pins may be used to support the abdomen if it is inclined to bend downward.

Fig. 63. – Another Method of Setting Butterflies and Moths.

As before mentioned, insects should be set soon after they are dead, while the parts are still soft and supple. But where this cannot be done, and the specimens have become stiff, brittle, and rigid, they must be 'relaxed' before any attempt is made at setting them out.

This process of relaxing consists in placing the specimens in a very moist atmosphere for a few days. There are several simple ways of doing this, many of which will readily suggest themselves to the reader. Your collecting box, if a zinc one, may also be used as a relaxer. Pin your stiff insects in it, after well moistening the cork, and simply shut them up for a day or two. Any metal box will serve the same purpose providing you put into it a piece of sheet cork on which to fix the insects, and this cork may rest on a bed of moist sand.

Another plan is to float the pinned specimens on corks in a shallow vessel of water, and cover them over with a bell glass.

Insects that are being relaxed should be examined from time to time, and the degree of flexibility acquired tested by a gentle pressure of the setting needle or by blowing on them. If not sufficiently supple, give another day in the damp cell, but never allow them to be forgotten till they are covered with mildew.

The time occupied in thoroughly drying butterflies and moths will vary considerably according to their sizes and the condition of the atmosphere. In hot and dry summer weather four or five days will prove quite sufficient for the very small and thin-bodied species. From one to two weeks, however, may be looked upon as the average period; but the large and thick-bodied moths may require more than this.

Perhaps the best test of their condition is the gentle pressing of the setting needle against the abdomen – the last part of the body to become dry and stiff. If the abdomen seems quite firm and rigid, you are pretty safe in removing the specimen from the board; but if it bends at all under a slight pressure of the needle let it remain for a day or two longer.

If your cabinet is quite ready for the reception of new-comers, the insects may be put in their proper places immediately after their removal from the setting boards; but if not, they may be pinned temporarily in a 'store box' till the time comes when you have proper accommodation provided. The full consideration of these matters will be dealt with in another chapter.

It is possible that the setting of some of your specimens will not exactly please you. If such is the case, put them in a relaxing box for a day or two, and then reset them more to your fancy.

We have now to deal with a matter that applies more particularly to moths, especially the very large and thick-bodied species. The abdomens of these become more or less contracted and shrivelled on drying, sometimes to such an extent as to look most unsightly.

There is a remedy for this, and the time and patience required in working it out will be well repaid by the superior results obtained.

While the abdomen is still in a soft condition, make a slit throughout its length with a very sharp knife or a sharp-pointed pair of scissors. This slit should be made down the centre of the under surface, or, if the insect is to be placed in the cabinet with the under side exposed, down the middle line of the back. Then remove all the contents of the abdomen, scraping them out with a piece of hooked wire, or removing them with a fine pair of forceps, and leaving the skin as clean as possible both within and without. Now introduce a packing of cotton wool, just sufficient in quantity to maintain the natural form of the body as the specimen dries.

There is another good method of stuffing moths that possesses a decided advantage over the one just described, since it leaves the specimen in such a perfect condition that it shows no appearance of having been stuffed when viewed from either side. This consists in snipping off the abdomen at the waist, clearing out the contents with a hooked wire, lightly stuffing it with cotton wool pushed in at the waist, and then setting it aside to dry, while the other part of the insect is undergoing the same process on the setting board. When both parts of the moth are thoroughly dry, the stuffed abdomen is easily fixed in its place with a little coaguline; and this, if neatly done, will not show the slightest sign of the treatment to which the insect has been submitted.

Even after your insects are finally housed in the cabinet, they are subject to two other dangers, both of which are more destructive to moths than to butterflies. One is technically known as 'grease,' and the other is the invasion of certain museum pests that feed on the specimens, causing them to fall to pieces.

Examine the moths that have been for a time in the cabinet, and some are sure to exhibit an oily or greasy appearance, the hairs of the abdomen, and perhaps also of the thorax, being clogged together just as if the specimen had been dipped in oil, the same miserable condition perhaps being shared also by parts of the wings.

This is due to the gradual oozing out of the fatty matter that is always present to a greater or less extent in the bodies of the insects, and which must necessarily show itself more sparingly in specimens that have been carefully stuffed.

The old saying, 'Prevention is better than cure,' applies well in the present case; but as there are times when a knowledge of the 'cure' is the only means of saving a valuable specimen from destruction, we will study both.

To deal with the two in the order of the well-worn proverb, we will consider the prevention first. Always carefully clean out and stuff the abdomens of large-bodied insects; and as a rule, treat them with some substance that will either absorb or dissolve out all oily matter. I think the best plan is to remove the abdomen, clean it out if its size permits of such an operation, and then, after labelling it to prevent its future application to the wrong body, either let it remain in a bottle of magnesia for several weeks, or soak it in benzole or ether for a few hours or longer.

If magnesia has been employed as an absorbent, you have simply to blow or lightly brush off the loose powder that clings to the body, and then fix it in its place with coaguline. A body dipped in ether or benzole will look as if completely spoilt at first, for the furry coat that clothes it will lie matted and almost entirely robbed of its beautiful colours, reminding one forcibly of the proverbial 'drowned rat.' But take no notice of this change. Let the body have at least a few hours in the liquid, extending the time to a day or two in the case of very large ones and those which experience has proved to be particularly liable to 'grease;' and, immediately on withdrawing it, fix it with a pin in a good strong draught, such as you may obtain by opening a window about an inch, or, if a breezy day, in the open air.

These liquids are so volatile (and for that reason should never be left exposed in an open vessel) that they rapidly evaporate, leaving the dry hair to be loosened by the breeze, thus bringing back the natural appearance almost perfectly.

It is probable that many of the smaller insects that were not considered to require the stuffing or grease-removing operations will sooner or later exhibit a greasy tendency in the cabinet. At first the abdomen is affected, and the oily matter then gradually creeps over the rest of the body, finally spreading over the wings, and giving the insect a most deplorable aspect. But these are not irreparably lost, and the following cure will often bring them back to their former beauty.

If the abdomen only shows signs of grease, cut it off and soak it in one of the above-named liquids for a day or so, replacing it as above after the drying operation. If, however, the oily matter has spread to the thorax and the bases of the wings, the whole specimen must be soaked, using a basin or jar of suitable size, covered with a plate of glass. A good draught during the drying operation will do much to prevent the hair from sticking in matted tufts close against the surface of the body and wings, and a gentle brushing with a very soft camel-hair brush will loosen and reset the fur.

The other danger to which we have referred is the invasion of certain 'mites' and other museum pests that pay periodical visits to our cabinet drawers and store boxes, often committing such havoc as to severely try the patience of an interested naturalist.

The way to prevent such intrusions is to make the atmosphere of the compartments so obnoxious (to them) that they dare not enter; and, further, to so spice up your specimens that they are no longer safely edible to the invaders.

The first object can be attained by always keeping camphor or naphthaline (albo-carbon) in each division. A lump of either substance may be secured by pins or a little perforated cell in the corner of each drawer or box, or the bottom of each may be dusted with finely powdered naphthaline; but as both these solids are volatile, care must be taken to renew the supply as occasion requires.

Then, with regard to the second precaution, perhaps nothing is more effectual than corrosive sublimate. A little of this may be dissolved in a small bottle of alcohol (spirits of wine), labelled with the name and the word Poison, and kept ready for use. All the skins of stuffed specimens should be painted with this solution, and the stuffing itself may be moistened with it before insertion.

There is yet another circumstance that renders a watchful care of your cabinet specimens necessary, if you happen to possess many that were captured 'at sugar.' Some of these will have so gorged themselves with syrup that they are literally full of it, and this will sometimes find its way to the outside, often dropping on the surface beneath. In such cases the sugar should be removed as completely as possible, and the bodies stuffed, before they are quite dry; but if the specimens have been in the cabinet so long that they are stiff and hard, the under sides of the abdomens may be completely cut out with a very sharp knife and thrown away, and then the sugar cleaned out from the upper shell as neatly as possible.

CHAPTER X

PRESERVING OVA, LARVÆ AND PUPÆ

Many young entomologists give their attention almost solely to the perfect forms of insects, often collecting and studying a very large number of species without regard to their earlier stages and metamorphoses. This is decidedly a very great mistake. Although the lifeless form pinned in a cabinet may be a most beautiful object in itself, yet a study of this alone is uninteresting compared with that of the wonderful changes it has undergone since the time it was a very young larva.

The different stages of the insects should be known as far as possible, and these, as well as the perfect forms, should be included in the collection for future study and reference. A good cabinet, according to my own opinion, is one that possesses, among other good features, a number of complete sets illustrative of the life history of at least the more typical forms; and as it is not a difficult matter to preserve the earlier stages, there is really no excuse for their omission from the collection.

The empty shells of ova are in themselves sometimes interesting objects, especially when they illustrate some peculiar instinct on the part of the parent. Sterile eggs, also, often fall into the hands of breeders and rearers, and these, though in other respects unprofitable, are useful in the cabinet.

If fertile eggs are to be prepared for a collection, they must be killed. This is easily done by thrusting into each one the point of a very fine needle, or by immersing them for a moment in boiling water, or by shutting them up in a bottle with camphor. In drying they often contract more or less, and frequently change their colour; still these are useful, providing notes have been taken of the characters thus lost. The larger eggs are capable of special treatment where the owner has the necessary time and patience, and where the highest results are desired. By means of a surgeon's injector of small size the contents of the eggs can be removed; and then, by the same instrument, a warm solution of gelatine, coloured in such a way as to restore the natural tint, may be forced into the empty shell. As the gelatine cools and hardens, it prevents any shrinking of the shell, and thus both form and colour are well preserved.

For the preservation of larvæ you will require one or two simple appliances.

The first of these is a suitable glass blowpipe, one form of which is here illustrated. It consists of a glass tube, one end of which has been drawn out very fine; a piece of watch spring tied to it in such a manner that it will hold the skin of a larva at the small end, and a piece of india-rubber tubing at the other end, pressed by means of a brass spring clip.

Fig. 64. – A Blowpipe for Larvæ.

A little drying oven is also very useful, but not absolutely necessary. If you decide to have one, any square box of sheet iron (not soldered tinned iron) may be readily converted into one. It must be provided with a hinged door in the front with a ventilator at the bottom, a hole for the escape of hot air at the top, and a tripod wire stand inside on which to rest the specimens while drying. The whole should be supported on a wire stand, so that heat may be applied below.

Each larva to be preserved should be dealt with in this way. First kill it by means of any one of the killing bottles or boxes already described, or by immersion in spirit of wine. When quite dead, enlarge the anal orifice by thrusting a needle into it, and then lay it on a piece of blotting paper with its head toward you. Now take a round ruler, previously covered with blotting paper, and roll the larva gently from head to tail till all the contents of the skin have been expelled. Next fix the skin on the fine end of the blowpipe, by thrusting the point of the latter into the opening, and allowing the spring to press gently on its edge. Gently blow into the skin till it is inflated just to a little below natural size, then either hold it near a fire or rest it in the drying oven till it is quite dry and rigid.

If you have done your work neatly, the skin and blowpipe will both be quite air-tight when the clip is closed; and the air, finding no outlet, will still further inflate the skin when it expands on exposure to heat. This is the reason why you are directed to blow it out to something short of the natural dimensions. If you find that this expansion causes the skin to stretch beyond its normal size, a little of the air must be allowed to escape while it is yet soft and flexible.