Directions for Collecting and Preserving Insects Part 10

_The Wickersheim Preserving Fluid._--This valuable preserving fluid has been known for some time, but is not very commonly used, on account of frequent disappointment due to the difficulty attending its preparation.

It is claimed for it that animal or vegetable bodies impregnated with it will retain their form, color, and flexibility in the most perfect manner. The objects to be preserved are put in the fluid for from six to twelve days, according to their size, and then taken out and dried in the air. The ligaments remain soft and movable, and the animals or plants remain fit for anatomical dissection and study for long periods, even years. It is said to be especially valuable for the preservation of larvae and soft-bodied insects. In order to perfectly preserve the colors, it is necessary to leave the specimens in the fluid, or, if they are taken out, they should be sealed up in air-tight vials or vessels.

The formula for the fluid is as follows:

Dissolve 100 grams alum, 25 grams common salt, 12 grams saltpeter, 60 grams potash, 10 grams a.r.s.enious acid in 3,000 grams boiling water.

Filter the solution, and when cold add 10 liters of the liquid to 4 liters of glycerin and 1 liter of methyl alcohol.

LABELING SPECIMENS.

_General Directions._--It matters little how much care and pains have been taken in the preparation and mounting of specimens, they will have little value unless accompanied by proper labels giving information as to locality and date of collection, name of collector, and a label or number referring to notebooks, if any biological or other facts concerning them have been ascertained. There should be pinned to the specimen labels referring to, or giving all the information obtainable or of interest concerning it. A somewhat different style of label will be found necessary in the case of the two forms of collections described in the foregoing pages, namely, the biological or economic collection, and the systematic collection. For the former, numbers may be attached to the specimens which will refer to the notes relating to the specimen or species. For the latter, in most cases, all necessary information may be recorded and made available by written or printed labels attached directly to the specimens. In most cases, however, I find a combination of these two systems convenient and desirable. The numbering system is very simple, and is the one which I have followed in all the species for which I have biological or other notes. It consists in giving each species, as it comes under observation, a serial number which refers to a record in a notebook. With this number may be combined, if convenient, the date of rearing or collection of the specimen, and also the locality and food-plant if known. The vast number of species represented in a systematic collection renders the numbering system entirely out of place and inadequate, and the labeling system alone is generally available. If it becomes necessary in the systematic collection to refer to food-plants or life-history or any other fact of interest, the numbering system should be used, and I recommend that the numbers be written in red ink on the labels, to distinguish at a glance the numbers referring to biological notes from other numbers that will occur in the collection.

_Labels for pinned Specimens._--The following labels should be employed in the collection: (1) _Locality label_, which should be as explicit as possible. (2) _Date of capture_, which is very useful and sometimes quite important in various ways. It indicates at what time additional specimens of some rare species may be secured, and greatly a.s.sists in elaborating the life history of the species, and in other cases a.s.sists in the correct determination of closely allied insects, which differ chiefly in habit or date of appearance. (3) _A label to indicate the s.e.x_. This label has recently acquired greater importance than formerly, on account of the value of the s.e.xual differences in the distinction of species. The well-known signs for male, female, and worker, printed in convenient form, are well adapted for collections. (4) _The name of the collector_. This label is of less value, but sometimes becomes important in determining the history of the specimen or the exact place of capture. The name of the species is not necessarily attached to all the specimens in a collection, and ordinarily will be placed with the first specimen in a series in the cabinet. This and other labeling of insects in cabinet is discussed in another place. Other labels are useful to indicate type specimens, namely, those of which descriptions have been drawn up and published, and which should be designated by a special label written by the author himself. Determinations by an authority in a special group should be indicated, and the labels placed on specimens by such an authority should not be removed.

It will not be found necessary to use a separate label for each of the data indicated above, and a single label may be made to combine many of them, as, except for the specific names of the insects themselves (which should always be on the lowermost label), most other words will bear abbreviation, especially localities and dates. "A combination label, which has given general satisfaction to all to whom it has been communicated, is a two-line label printed in diamond type, on heavy writing paper. The upper line consists of the name of the locality, _e.

g._, 'Washngtn' (a name consisting of more than eight letters to be abbreviated), and the lower line has at the right-hand corner 'DC'

(interpunctuation and s.p.a.cing to be avoided so as to save s.p.a.ce). This leaves on the second line sufficient room for inserting the date, which can be quickly and neatly written with ink if the labels are printed in columns of ten or more repet.i.tions. The label thus combines locality with date of capture. Or the upper line reads 'Arizona' and the lower line 'Morrison,' the label thus combining locality with the name of the collector."[8]

[8] E. A. Schwarz, Proc. Ent. Soc., Wash., II, No. 1, 1891.

In general I indorse the system of labeling suggested in the above condensation from Mr. Schwarz, but there is no particular disadvantage, and in fact many advantages, in special cases, in a larger label or in folded labels. Particularly in visiting large foreign collections I have found it convenient to use large labels of thin paper which will contain a good deal of information closely written in pencil and bear folding several times, so as not to occupy more than the ordinary label s.p.a.ce when pinned to the specimens. This involves detaching the label when the specimen or species comes to be studied, but this additional labor is insignificant compared with the large amount of valuable information which in time is thus brought together in condensed availability for the student; for brief notes of opinions of experts, of comparison with types, of special studies, of reference to descriptions, etc., may thus be all brought together. Where there is not room to indicate the authority for a determination on the upper side of a label, I also find it convenient to do so on the lower side.

[Ill.u.s.tration: FIG. 116.--Cabinet for apparatus used in mounting and labeling. (Original).]

_Labeling alcoholic Specimens._--Alcoholic specimens, including alcoholic biologic material and collections of Arachnida and Myriapoda, are well adapted to the labeling system, as the vials are always of sufficient size to allow the insertion of one or more labels large enough to contain a pretty full record of the specimen. The label may consist of a number referring to notes, or of a number together with the other data indicated for the systematic collection. The label in my experience is preferably written in pencil, which, in alcohol, is practically permanent. Waterproof inks are sometimes used, and of these the oak-gall ink is undoubtedly the best. Dr. George Marx, in labeling his Arachnida, uses onion-skin paper and waterproof ink, such as Higgins's drawing ink. There is some danger, in placing a label in a vial, of its settling against the specimen and injuring it. This, however, can generally be avoided if a little care is used. The label may be long and narrow and folded lengthwise so as to occupy one side only of the vial, or short and inserted in such manner that it will pa.s.s around the inside of the vial, where it will be held by the natural adhesion to the gla.s.s in the upper portion of the vial, as shown at Fig.

114.

_Cabinet for Apparatus._--The work of preparation of insects for the cabinet may be greatly facilitated if a convenient case is provided with drawers and compartments for the keeping of pins of different sizes, labels, braces, implements, tweezers, dissecting apparatus, and the like, with microscopical supplies--slides, cover gla.s.ses, mounting media, etc. I present a photograph of a cabinet of this sort used in my earlier work and found very convenient and serviceable (Fig. 116).

INSECT BOXES AND CABINETS.

_General Directions._--The boxes or cases which are used to keep insects in permanently may be made of any dimensions to suit the fancy, 12 by 16 inches inside being a convenient size and allowing economic use of cork.

They must, however, be perfectly tight and should not be more than 2 inches deep on the inside. The bottoms should be lined with something which will hold the pins, and the whole inside covered with white paper, which, if delicately cross ruled, will facilitate the regular pinning of specimens. While the size and style of the box and cabinet may be left to individual taste, some choice must be had of material. _Red cedar should never be used._ I have learned, to my sorrow, the baneful effects of this wood, notwithstanding it is recommended--evidently by those who are guiltless of having used it--as having the advantage over other wood of keeping off museum pests. It seems impossible to get this wood so seasoned but that a certain amount of resin will continually exude from it; and insects in boxes of this material are very apt to soften and become greasy. Paper boxes are also bad, as they attract moisture and cause the specimens to mold. Well-seasoned pine and whitewood are the most satisfactory; and, in such boxes as have gla.s.s covers and are intended to form part of a neat cabinet for parlor ornament, the fronts may be of walnut or cherry.

The character of the boxes and cabinets used for storing insects will depend largely on the nature and extent of the collection and the object of the collector. For temporary use, nothing is more convenient and economical than a cigar box lined with cork or pith. Such boxes, however, should be employed only for the temporary storage of fresh specimens, as they afford free access to museum pests, and insects kept in them for any length of time are apt to be destroyed or rendered useless.

_The Folding-box._--The use of folding-boxes for the working collector is to be especially recommended in the case of those orders comprising small insects like Coleoptera, Hymenoptera, etc. These boxes have the great advantage of being readily rearranged on the shelves and of being very easily used in study. The boxes of this type now manufactured by John Schmidt, of Brooklyn, N. Y., and John Burr, of Camden, N. J., based on the experience which I have had, have proved so serviceable and satisfactory in this respect that I have employed them for the bulk of the collection in the National Museum. These boxes (Fig. 117) are constructed as follows:

[Ill.u.s.tration: FIG. 117.--The Schmidt folding insect box, opened and showing arrangement of insects (original).]

They are of white pine, sh.e.l.lacked and varnished, the bottom and top double and crossgrained, to prevent warping, and projecting slightly at all sides except the hinged back. They are 13 by 8 inches outside measurement. The inside measurement is 11 by 7. The sides, back, and front are five-sixteenths of an inch thick, with a machine joint, which is neat and very secure. The boxes are 2 5/8 inches in outside depth, unequally divided, the lower portion 1 inches outside depth, lined inside with a thin whitewood strip, projecting three-fourths of an inch above the rim of the outside box. Over this projecting lining the lid closes as tightly as practicable and is kept from springing by hooks and eyes. The bottom is cork-lined and covered with a fine, white, glazed paper.

Similar folding boxes with both sides of equal depth and both lined with cork, when properly covered, may be made to look like books and be set on end in an ordinary bookcase, but the single lining is preferable, as there is less danger of the breakage of specimens and the boxes may either be laid flat one on the other on shelves, or, what is more convenient, placed side by side resting on the front edge, so that the label is attached to one of the narrow ends. The rows of insects are then pinned crosswise, not lengthwise, of the box, with the abdomens turned toward the front which rests on the shelf.

All the boxes are furnished with neat bra.s.s label-holders, in which a card containing a list of the contents can readily be placed and removed at pleasure. The chief demerit of this box which I have endeavored to overcome by the above details is the tendency to warp and crack in the trying steam heat of our Government buildings.

_The Cabinet._--For larger insects, such as Lepidoptera, Neuroptera, etc., a larger box is desirable, and for these orders I have adopted for use in the National Museum a cabinet which resulted from a careful study in person of the different forms and patterns used for entomological collections both in this country and Europe, whether by private individuals or public inst.i.tutions. The drawer and cabinet are essentially after the pattern of those used in the British (South Kensington) Museum, but adapted in size to our own requirements. In the use of the National Museum these cabinets have proved eminently well adapted to their object.

[Ill.u.s.tration: FIG. 118.--Construction of insect cabinet drawer of the National Museum. A, cross-section _f_ front; B, same _f_ side; C, view of front end of side, 2/3 natural size (original).]

The drawers (Fig. 118, A, B, C) are square, with an outside measurement of 18 inches and an outside depth of 3 inches. The sides and back have a thickness of three-eighths of an inch, while the front is five-eighths of an inch thick. The pieces are firmly dovetailed together, the front being clean and the dovetailing blind. The bottom, _a_, is of three-ply crossgrained veneer, run into a groove at the sides, leaving a clear inside depth of 2 1/16 inches to the frame of the cover. The bottoms are lined in all but forty of the drawers with first quality cork, _b_, one-fourth of an inch thick. At a distance of one-fourth of an inch from the sides and back and three-eighths of an inch from the front there is an inside box of one-eighth inch whitewood, _c_, closely fitted, and held in place by blocks between it and the outer box. There is thus between the inner and outer box a clear s.p.a.ce, _d_, all round, in which insecticides or disinfectants can be placed to keep out Museum pests, making it impossible for such to get into the inner box containing the specimens without first pa.s.sing through this poison chamber. The entire inside is lined with white paper, or, in the case of the uncorked boxes, painted with zinc white. The front is furnished with a plain k.n.o.b. The cover is of gla.s.s, set into a frame, _f_, three-fourths of an inch wide, three-eighths of an inch thick, with a one-fourth inch tongue fitting closely into the s.p.a.ce between the inner lining and outer box, which here serves as a groove. This arrangement furnishes a perfectly tight drawer of convenient size and not unwieldy for handling when studying the collection.

The material of which these drawers are made is California red wood, except the cover frame, which is mahogany. The cabinets containing these drawers are 36 inches high, 40 inches wide, 21 inches deep (all outside measurements), and are closed by two paneled doors. Each cabinet contains twenty drawers in two rows of ten each, and the drawers slide by means of a groove, _g_, on either side, on hard-wood tongues, and are designed to be interchangeable.

_The Lintner display Box._--For beauty and security and the perfect display of the larger _Lepidoptera_, I have seen nothing superior to a box used by Mr. J. A. Lintner, of Albany, N. Y. It is a frame made in the form of a folio volume, with gla.s.s set in for sides and bound in an ordinary book cover. The insects are pinned onto pieces of cork fastened to the inside of one of the gla.s.s plates and the boxes may be stood on ends, in library shape, like ordinary books. For the benefit of those who wish to make small collections of showy insects, I give Mr.

Lintner's method, of which he has been kind enough to furnish me the following description:

Figs. A, B, and C represent, in section, the framework of the volume, _a_ showing the ends, _b_ the front, and _c_ the back. The material can be prepared in long strips of some soft wood by a cabinet-maker (if the collector has the necessary skill and leisure for framing it) at a cost of 60 cents a frame, if a number sufficient for a dozen boxes be ordered. Or, if it be preferred to order them made, the cost should not exceed 80 cents each.

Before being placed in the hands of the binder the mitering should be carefully examined and any defect in fitting remedied, so that the gla.s.s, when placed in position, may have accurate bearings on all the sides. The interior of the frame is covered with tin foil, made as smooth as possible before application, to be applied with thoroughly boiled flour paste (in which a small proportion of a.r.s.enic may be mixed) and rubbed smoothly down till the removal of the blisters, which are apt to appear. The tin foil can be purchased, by weight, at druggists', and the sheets marked off and cut by a rule in strips of proper width, allowing for a trifle of overlapping on the sides. Its cost per volume is merely nominal.

First-quality single-thick gla.s.s for sides must be selected, wholly free from rust, veins, air-bubbles, or any blemish. Such gla.s.s can be purchased at 15 cents a pane. The lower gla.s.s, after thorough cleaning, especially of its inner surface, with an alkaline wash, and a final polis.h.i.+ng with slightly wetted white printing paper, is to be firmly secured in its place by a proper number of tin points; the upper gla.s.s is but temporarily fastened. The binder must be directed to cover the exposed sides of the frame with "combed" paper, bringing it over the border of the permanent lower gla.s.s and beneath the removable upper gla.s.s.

[Ill.u.s.tration: FIG. 119.--Construction of the Lintner box.]

The covers of the volume are of heavy binders' board (No. 18), neatly lined within with glazed white paper. On one of the insides of the lids may be attached, by its corners, a sheet with the numbers and names of the species contained in the volume, or these may be placed on the pin bearing the insect. If bound in best quality of imitation morocco, with cloth covers, lettered and gilded on the back, the cost (for a dozen volumes) need not exceed $1 each. If in turkey morocco, it will be $1.50.

The lettering and ornamentation of the back will vary with the taste of the individual. The family designations may be permanently lettered, or they may be pasted on the back, on a slip of paper or gum label, as are the generic names, thus permitting the change of the contents of a volume at any time if desired.

The bits of cork to which the insects are to be pinned are cut in quarter-inch squares from sheet-cork of one-fourth of an inch in thickness. If the trouble be taken to trim off the corners, giving them an octagonal form, their appearance will be materially improved and much less care will be required in adjusting them on the gla.s.s.

The cement usually recommended for attaching the cork to the gla.s.s is composed of equal parts of white wax and resin. My experience with this has not been favorable, for, after the lapse of a few years, I have invariably been subjected to the serious annoyance of being compelled to renew the entire contents of the volume, clean the gla.s.s, and replace the corks with new cement. From some cause, inexplicable to me, a gradual separation takes place of the cork with its cement from the gla.s.s, first appearing at the angles of the cork, and its progress indicated by an increasing number of iridescent rings which form within until the center is reached, when, if not previously detached, the insect falls with the cork, usually to its injury and that of others beneath it.

A number of years ago I happened to employ, in attaching a single piece of cork in one of my cases, a cement originally made for other purposes, consisting of six parts of resin, one of wax, and one of Venetian red.

Several years thereafter my attention was drawn to this piece by finding it as firmly united as when at first applied, and at the present time (after the lapse of twelve years) it is without the slightest indication of separation. Acting upon this hint, I have, of late, used this cement in the restoration of a number of my cases, and with the most satisfactory results. It is important that the cement, when used, should be heated (by a spirit lamp or gas flame) to as high a degree as it will bear without burning. An amount sufficient to cover the bottom of the small, flat metal vessel containing it to the depth of an eighth of an inch will suffice and prevent the cork from taking up more than its requisite quant.i.ty. It should be occasionally stirred to prevent the precipitation of its heavier portions. The cork may be conveniently dipped by the aid of a needle inserted in a handle, when, as quickly as possible, it should be transferred to the gla.s.s, for the degree of adhesion seems to depend upon the degree of fluidity of the cement. From some experiments made by me, after the corks had been attached as above, in heating the entire gla.s.s to such a degree as thoroughly to melt the cement until it spreads outward from beneath the weight of the cork, and then permitted to cool--the gla.s.s meanwhile held horizontally, that the corks might not be displaced--the results appear to indicate that the above cement, applied in this manner on gla.s.s properly cleaned, will prove a permanent one. It is scarcely necessary to state that this method is not available where the gla.s.s has been bound as above.

Preparatory to corking the gla.s.s for the specimens a.s.signed to it, the s.p.a.ces required for them are to be ascertained by arranging them in order on a cork surface or otherwise. On a sheet of paper of the size of the gla.s.s, perpendicular lines, of the number of the rows and at their proper distances, are to be drawn, and cross lines equal in number to the insects contained in the rows. The distances of these lines will be uniform, unless smaller specimens are to occupy some portion of the case, when they may be graduated to the required proportion. With the sheet ruled in this manner and placed beneath the gla.s.s, the points where the corks are to be applied are indicated by the intersections of the lines. The sheet, marked with the family of the insects for which it was used and with the numbers designating its divisions, may be laid aside for future use in the preparation of other cases for which it may be suitable. In a series of unbound cases in my collection, in which the gla.s.ses measure 11 by 14 inches, I have used for my Lepidoptera and laid aside the following scales, the citation of which will also serve to show the capacity of the cases: 3 by 8, Catocalas; 2 by 7 and 3 by 9, Sphingidae; 4 by 11 to 4 by 14, Bombycidae; 5 by 13 to 6 by 16, Noctuidae; 8 by 16 and 8 by 20, Lycaenidae and Tortricidae.

The unbound cases above referred to are inexpensive frames, made by myself, of quarter-inch white wood or pine, the corners mitered, glued, and nailed with three-quarter inch brads, lined within with white paper (better with tin foil), and covered without with stout manila paper. The gla.s.ses are cut of the size of the frame, and when placed in position thereon are appressed closely to it by laying upon them, near each corner, a heavy weight, and strips of an enameled green paper, cut to the width of 1 inch, are pasted over their edges, extending a little beyond the thickness of the frame, and brought downward over the outside of the frame. On its back two gum labels, indicating the insects inclosed, are placed at uniform heights (7 and 12 inches), when, if all has been neatly done, they present a tasteful appearance upon a shelf.

When there is reason to believe that the case will need to be opened for the change or addition of specimens, it will be found convenient to employ, for the fastening of the left-hand side of the upper gla.s.s, paper lined with a thin muslin, to serve as a hinge when the other sides have been cut.

Should it become desirable to bind these cases, outside frames may be constructed after the plans above given, with the omission of the inside quarter inch (the equivalent of these frames), in which these may be placed and held in position by two or three screws inserted in their sides.

_The Martindale Box for Lepidoptera._--Mr. Isaac C. Martindale, in the October, 1891, number of _Entomological News_, pp. 126, 127, describes a new form of cabinet for b.u.t.terflies, the drawers of which present some new features. They are for the same end as the Lintner box described above--namely, for the display of the upper and under surface of the wings of Lepidoptera, and promise to be more useful. The drawer is described as follows:

The especial feature is the drawer itself, which, instead of having a cork bottom, as is usually the case, has both the top and bottom of gla.s.s. The top part of the drawer frame fits tightly over a ledge one inch in height, effectually preventing the intrusion of destructive insects, the pest of the entomologist; but it is readily lifted when it is desirable to add to the contents or change the location of the specimens. For the inside arrangement I have taken a strip of common tin, one inch wide, and turned up each side five-sixteenths of an inch, thus leaving three-eighths of an inch for the bottom. The length of the strip of tin, being about two inches longer than the width of the drawer, admits of each end being turned up one inch. Into this tin trough is tightly fitted a cork strip three-eighths of an inch square.

The whole being covered with white paper, such as is usually used for lining drawers, conceals the inequalities of the cork and makes a fine finish. They should be made to fit neatly in the drawer, and can be readily moved about to suit large or small specimens. For _Lycaenas_, _Pamphilas_, etc., as many as fifteen of these strips may be used in one drawer, and as few as five for _Morphos_, _Caligos_, etc. The upturned ends are fastened in place by using the ordinary thumb tacks that can be procured at any stationer's. The frame work of the drawers should be of white pine, well seasoned. Into this the thumb tacks are readily inserted and as easily withdrawn when a change in the position of the cork strips is needed.

_Horizontal vs. vertical Arrangement of Boxes._--I have elsewhere discussed the availability of the upright vs. the horizontal arrangement of insect boxes.[9] In the case of Lepidoptera and large-bodied insects I have found the horizontal drawer or box to be preferable. If large-bodied insects are placed in a vertical position they are very liable to become loose on the pins, swing from side to side, and damage themselves and other specimens; but for the smaller insects of all orders, the vertical arrangement is quite safe and satisfactory. If the pin is slightly flattened, as described on p. 69, the danger of large specimens becoming loose is to a great extent avoided.

[9] _American Naturalist_, Vol. XV, p. 401, 1881.

_Lining for Insect Boxes._--The old lining of insect boxes was the ordinary sheet cork of commerce, and if a good quality of cork is procurable it will answer the purpose. A better substance, however, for the lining of insect boxes is the prepared or ground cork, which is now almost exclusively used. It is simply ground cork mixed with a small amount of glue, compressed into sheets and covered with paper. This gives a very h.o.m.ogenous composition, and is much better than the ordinary cork, having a more uniform and neat appearance, and admitting the insertion of the pins more freely. It may be purchased from H.

Herpers, 18 Crawford street, Newark, N. J.

A less expensive subst.i.tute is paper stretched upon a frame. Prof. E. S.