How to Pin Butterflies
The most important part of spreading butterfly wings is to soften the specimen properly in a relaxing chamber. The relaxing chamber can be a plastic container (Tupperware) lined with a wet cloth or toweling (use water to dampen cloth). Put a few moth crystals in the container to prevent mold.
Lay the butterfly or several specimens on the wet cloth (you can leave papered butterflies in envelope) and cover for 12-24 hours. The specimen is now relaxing which means absorbing moisture into its body and veins and wings. The trick to knowing if the butterfly is relaxed enough to spread is that it should feel very much like a live specimen with movable wings, antennae etc. Large or stout bodied butterflies will take longer to relax. Some people inject the butterfly thorax with hot water and then relax it for a few to several hours, this is called speed relaxing. This technique also makes it easier to spread stout bodied species.
1 ) After the butterfly has relaxed properly, hold it by the thorax and squeeze gently or pinch thorax and wings will open slightly.
2) While squeezing thorax to separate wings, carefully insert an insect pin through the thorax about half way.
3) Holding the pinned butterfly, place the body in the groove of a spreading board and push the pin into the groove to hold butterfly in place.
4) After the thorax is pinned in the groove, place thin strips of paper (or index card) over each side of the wings, close to the body, holding the wings down. Use pins near to the wings but not through the wings to hold the paper strips down.
5) Using spade tip forceps, maneuver each forewing and hindwing individually until the lower edge of the forewings are horizontal and a V forms when the hindwings lift up to meet them. Antennae should form a V extending outward. Wing edges can be covered with paper to prevent curling.
Dry butterfly on board 24-48 hours. Remove all pins carefully except the pin through the thorax. Pin the butterfly in your display case. Most breaks can be repaired with clear glue.
The best spreading boards are covered in balsa wood and have an adjustable groove. Youngsters can use a piece of flat styrofoam with a slot cut out to accommodate a butterfly body.