Immature stages. Eggs can be preserved in alcohol. Caterpillars can be killed in a preservative fluid (i.e., KAAD) or boiled (like shrimp!), and then stored in 70% (rubbing) alcohol. Pupae can be preserved in alcohol, frozen and mounted on an insect pin; or preferably the butterfly can be allowed to emerge and the pupal skin can then be pinned underneath the mounted butterfly.
Collecting, killing and storing specimens. After netting a butterfly in an aerial net, the best way to kill it is by pinching its thorax (middle body segment) between your thumb and forefinger. This technique takes some practice to learn the proper pressure, but it will quickly stun the specimen and prevent it from damaging itself. With its wings over its back, the specimen can then be slipped into an envelope or a paper triangle or envelope. Specimens can be kept in this condition indefinitely in a tight-fitting box with moth balls or other insecticide, until they are “relaxed” for mounting. Alternatively, freshly collected specimens can be stored in a plastic bag in a freezer until they are mounted, eliminating the need to “relax” the specimen before mounting.
“Relaxing” dried specimens. After insects are dead, they become extremely brittle. However, dried specimens can always be relaxed and mounted in any desirable position. Relaxing chambers can be made from jars or plastic boxes. Place a piece of folded paper towel on the bottom and moisten it with water. To prevent mold from growing on specimens, add an antiseptic (chlorocresol or Glanz Relaxing Fluid from the Bryanston Corp. are sold through chemical and entomological supply catalogs, but Lysol® can work as well). In the closed container, high humidity will “relax” the specimen over time (2 days for small specimens and 5 to 7 days for larger ones).
Pinning the specimen. After relaxing the specimen, remove it from its envelope carefully. Holding the specimen by the thorax, force an insect pin through the middle of the thorax (middle body segment) between the wings. The wings may be forced backwards in order to insert the pin far enough through the body. After pinning, it is helpful to force the wings down with forceps. This step makes the specimen easier to manipulate once it is positioned on the mounting board. Next, pin the specimen onto the mounting board, being certain to keep the side of the butterfly, where the wings are hinged to the body just above the surface of the mounting board.
Mounting the wings, body and antennae. When the specimen has been properly placed on the mounting board, wings can be folded down using strips of paper and pins. Avoid touching the wing surfaces with your fingers which would rub off scales. Once both pairs of wings are pinned down underneath paper strips, use insect pins to pull the front wings forward individually, alternately or both at the same time to avoid twisting the body around the pin. Be certain to only insert pins into the wings right behind larger wing veins so not to rip the wings. Move the front wings forward far enough so that their hind margins form a nearly straight line. Move the hind wings forward underneath the forewings to match the color patterns. Next, pay attention to the antennae and the abdomen, pinning then into their proper positions. Check the overall position of the specimen and make any adjustments necessary before moving the pins from the ends of the paper strips to just outside the wing margins, tightening the paper strips in the process. Place wider pieces of paper on the remainder of the exposed wing surface to keep prevent curling. Drying time usually takes several days to a week and will depend on specimen size, temperature and humidity. After the specimen is dry, carefully remove the pins and discard paper strips.
Note for specimen preparation for use in shadowbox and dome displays: By making mounting boards from balsa wood with a 90 to 45 degree angle between mounting surfaces, specimens can be mounted for display in a dome in a more natural position. However, only pin specimens that have been stored dry, since insect pins can not be easily removed from freshly killed and mounted specimens. After drying the specimen rub off hairs and remove legs necessary to glue the specimen on the background cloth or object in the display and remove the pin.
Storage of mounted specimens. Keep mounted specimens in tightly-closed boxes. If specimens are to be stored for long periods in dark conditions add moth balls, paradichlorobenzene crystals or other registered insecticide to prevent dermestid (carpet) beetles and book lice from feeding on the body parts (note: moth balls will melt Styrofoam). If the specimens are kept in lighted conditions, such as in glass frames or domes, generally no insecticides are necessary since insects that feed on dead insects (book lice, dermestid or carpet beetles) do not like light. However, keep them out of direct sunlight to avoid fading of pigment colors. Always keep specimens in low moisture conditions to prevent mold from growing on the specimen’s bodies. Stored properly, specimens will last for years and years.