Though there is no international authority mandating standards for the collection and preservation of specimens of insects and similar invertebrates, entomology has been an amateur and scientific activity for over two centuries. During this period practices varied widely and in many respects commonly differed greatly from modern practice. However, by the mid-twentieth century a range of technique and of equipment had emerged that amount to a de facto standard. Although there is some flexibility concerning the details, practitioners who diverge too widely from that standard are likely to find their work ignored as unacceptable anywhere in the modern world. One beneficial effect of the standard is that equipment and supplies have become available for practically any aspect of collection, preservation and documentation of specimens. The best-known format for insect collection is dry mounting and labelling on pins, and for many types of specimen this is likely to remain so for the foreseeable future. Pinning is a range of techniques for which the equipment has changed only slightly in recent decades but it is not the only one of importance in entomology. Other means of mounting include:
various kinds of slides for microscopes and projectors;
freeze-drying of specimens with labile coloration; and
wet preservation of several types.
Research into improved methods of presentation and handling continues, each requiring its own equipment.
Pinning of entomological specimens
Entomological pins. Continental pins, so called for historical reasons, are used internationally by museums and collectors. They are made of stainless steel for preference, especially for very long-term storage of specimens, but blackened steel also is used. The pins have round plastic or solid metal heads. Continental pins are of a standard length, but they are available in thicknesses numbered 000, 00, 0, 1, 2, 3, 4, 5, and 6. This standard pin length is sufficient to accommodate an adequate number of data labels and to permit convenient handling with suitably curved forceps.
As an exception to this standard, there also are pins of size 7, extra-long and very strong pins for very large beetles; they are 52mm long and thicker than size 6 pins.
Direct Pinning. Direct pinning is the insertion of an entomological pin directly through the thorax of a specimen. The insects are pinned vertically through the thorax with a suitably sized pin, but by convention they are not pinned on the midline, but to the right, so as to leave at least one side undamaged.
Point. A point is a triangular piece of white card. Specially designed point punches permit the production of large numbers of points of standard sizes as required. To use a point, insert a pin is inserted through the broad base of the triangle. To mount the specimen, place a tiny amount of glue on the tip and apply it to the right side of the insects thorax. If appropriate the tip of the point may be bent at the necessary angle to hold the body of the specimen horizontal when the pin is vertical, with the long axis of the insect at right angles to the point.
Minuten pins. Insect pins without heads, 12mm long. They are used for double mounting very small insects. They also may be used profitably for staging insects of moderate size, where they have the advantage of being less damaging to the specimen. For best effect in that respect, the pin is inserted from below through the staging card, well into the thorax, but not all the way through. Alternatively the minuten pin can be inserted laterally into one side of the thorax, again preferably not all the way through.
Carding. Insects are glued to rectangular pieces of acid free card or Bristol board providing a stage. Typical sizes are 4.5 x 11 mm;5 x 14 mm;6 x 17 mm;10 x 21 mm;13 x 30 mm. Printed lines allow uniform placement of the entomological pin. Though this is convenient, it is dubious practice at best, because it obscures features that might be necessary for taxonomic or morphological studies. In any case, at the very least the glue should be sufficiently conveniently soluble to be removed with solvents when necessary. With such considerations in mind, Canada balsam is about as good an adhesive as any.
Staging. When specimens are mounted on a smaller support which in turn is supported on a normal full-sized entomological pin, this is called staging. For example a specimen might be mounted on a minuten pin, typically being pinned on its side or upright with the minuten pin driven into a stage, a strip of suitable material such as dried plant pith or plastic foam supported in a horizontal position on the main entomological pin; as a rule a number 3 pin is convenient. Other forms of stage include card mounts and point mounts.
