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Killing and Preserving Insects
The use of alchohol or formalin is the most satisfactory method of killing most soft-bodied insects. Those with harder bodies should be dropped into a cyanide bottle or they may be killed with chloroform.
The Cyanide Bottle.--The cyanide bottle is prepared by taking a large quinine bottle or morphine bottle or one of the stout roundbottomed neckless tubes, putting into it a few small lumps of cyanide of potassium and pouring over them a semi-fluid mixture of plaster of paris and water. The bottle is then left open for a few hours until the plaster of paris thoroughly dries. The purpose of the plaster is to prevent the moisture from the deliquescing cyanide from reaching the insects and it is well also to put a piece of blotting paper over the plaster. When one is collecting insects it would be well to cut into strips some soft absorbent paper and stick the slips into the bottle in such a way that the insects' bodies will not rattle about too much.
Preparing Insects for the Cabinet.--In mounting insects for the cabinet no pins should be used except those made especially for mounting specimens. The long German pins are much to be preferred to the short English ones. The best are the Klaeger pins, the Carlsbad pins and the Vienna pins, all of which can be purchased from the dealer in entomological supplies. The Japanned black pins are the best for most insects since they are not ruined by the verdigris which issues from the bodies of many insects. Specimens should be prepared for the collection as soon after death as possible. If they have been collected in the forenoon they should be mounted the same evening--where possible. Most of the insects which we consider in this book should be pinned through the thorax. Grasshoppers and locusts should have one pair of wings spread. Dragon-flies and most other Neuropterous insects should have both pairs of wings spread. For this purpose a spreading board is necessary. Excellent spreading boards are for sale by the dealers but very good ones can readily be made. The spreading board in use for Lepidoptera will answer admirably for any of these insects. One is shown at Fig. 260 and needs no extended description except to state that the central grove in which the body of the insect rests should be bottomed with cork or some soft substance into which the pin can be inserted. While spreading, the time required for drying must be determined by experiment for a given locality and given time of the year since it depends upon the dryness of the atmosphere.
Insects which are too small to pin are preferably mounted upon little triangular cardboard tags. They are glued to the tip of the triangle, the pin being thrust through the base. White shellac or yellow shellac are good substances to use for the glueing. Most of those minute insects may be mounted to advantage on the side with the back away from the pin, and it is generally advisable to mount them with the side uppermost. It must be remembered that while an insect has one back and one belly it has two sides. Punches for cutting tags for this purpose may be purchased from the dealers. After the insect is pinned and dried great care should be taken with the labelling. In all cases the date and the actual locality should be entered upon the label, and, if the locality is such that there is some doubt that the elevation can in future be ascertained with ease, the elevation should be also placed upon the label. The name of the collector should be stuck on the same pin, and the name of the insect upon another label on the same pin. That will make three labels, one with the name, one for the collector, and one for the exact locality and date. All labels should be as small as possible, and should be printed in diamond type. After the labelling is done the specimens are ready for the cabinet.
The Cabinet.--In the matter of a cabinet there is considerable room for the judgment of a collector. The so-called Schmidt insect box is an excellent box for a more or less temporary collection, and, in fact, there are many specimens in the museums which have been preserved in these boxes for many years. They are of small and convenient size, book form, cork-lined, tightly constructed, and close very tightly. An insect cabinet with sliding drawers, glass-covered, can be made by any good carpenter, but great care should be taken to make the joints of the drawers absolutely air-tight. When a collection becomes infested with museum pests or mites or Psocids, it can easily be disinfected by pouring into the box bisulphide of carbon. Great care must be used in the handling of this substance, however, as it is inflammable. After the drawer has become disinfected, a teaspoonful, moreor less, of naphthaline will act as a deterrent against the entrance of other insect pests. For soft-bodied insects which must be kept in liquid, either alcohol or formalin, a permanent arrangement is a very difficult matter. A vial-tray in use by some collectors is a good idea. The one invented and used by Dr. George Marx is shown in the accompanying figure. In mounting insects for the microscope Canada balsam is the best medium for most of them, but it must be remembered that with soft-bodied forms fresh mounts will cloud unless the water has been extracted by passing through successive strengths of alcohol.