How to Preserve a Butterfly: Pinning, Drying, and Display

Preserving a butterfly involves killing or finding a fresh specimen, softening its body if it has stiffened, pinning it through the thorax, spreading the wings symmetrically on a flat board, letting it dry completely, and then storing it in a sealed case safe from humidity and pests. The full process takes about a week of mostly hands-off drying time, and the materials are inexpensive. What separates a museum-quality mount from a crumbling mess usually comes down to patience during the spreading step and vigilance about pest protection afterward.

Starting With a Fresh or Recently Dead Specimen

The easiest butterfly to preserve is one that died recently and is still flexible. Butterflies found dead outdoors, raised from caterpillars, or ethically collected while fresh give you the most options. If you raised the butterfly from a chrysalis and it has died naturally, you can begin working with it almost immediately. If you found one outside, check that the wings are intact and the body is not desiccated. A butterfly whose abdomen feels hard and whose wings resist movement has already dried and will need to be relaxed before you can spread it.

For collectors who catch live butterflies, the standard method is to place the specimen in a kill jar or a freezer. Freezing for 24 to 48 hours is the simplest approach for beginners: put the butterfly in a small container with a piece of tissue to absorb moisture, then freeze it. This avoids the chemicals involved in traditional kill jars and works reliably for most species. Once the butterfly is dead and still pliable, you can move straight to pinning.

Relaxing a Butterfly That Has Already Dried

Dried butterflies are brittle. If you try to move their wings without rehydrating them first, the wings will crack and the legs will snap off. To make the body pliable again, you need a relaxing chamber, which is just an airtight container with a damp environment inside.

A simple version uses a plastic food container with a layer of wet paper towels or damp sand on the bottom. Place the butterfly on a small piece of cardboard or foam above the moisture so it is not sitting in water directly. Seal the container and leave it for one to three days, depending on the size of the specimen. Larger butterflies with thicker bodies take longer. You want the joints to move freely when you gently test them with forceps. Adding a few drops of antiseptic, like a tiny amount of household disinfectant, to the water helps prevent mold from growing in the humid chamber while you wait.

The risk with relaxing is oversaturation. If the butterfly sits too long or touches standing water, the scales on the wings can lift or the colors can bleed. Check it daily and remove it as soon as the wings flex without resistance.

Pinning Through the Thorax

Entomological pins are not regular sewing pins. They are longer, thinner, and made from stainless steel or black-enameled steel that resists corrosion over decades. Sizes range from 000 (very fine) to 7 (thick), and for most medium-sized butterflies, a size 2 or 3 pin works well. Smaller species like blues and hairstreaks may call for a size 0 or 1. You can find entomological pins at biological supply companies for a few dollars per hundred.

Push the pin straight down through the center of the thorax, which is the middle section of the body between the head and abdomen. The pin should go in vertically, not at an angle, so the butterfly sits level. Leave about a centimeter of pin above the thorax so you have room to handle it without touching the specimen. The pin exits through the underside and sticks into whatever surface you use for spreading.

Spreading the Wings

Spreading is the step that makes or breaks the final result. A spreading board is a flat surface with a groove down the center sized to cradle the butterfly’s body, with flat panels on either side where the wings rest. You can buy commercial spreading boards made from balsa wood or soft foam, or you can make one from two strips of foam board with a gap between them.

Pin the butterfly into the groove so its body sits in the channel and the wings lie flat on the panels. Then use strips of wax paper, tracing paper, or glassine pinned down over the wings to hold them in position. Slide the wings into their final pose by gently pressing on the wing veins through the paper strips with a pin or a fine needle. Never push directly on the wing membrane itself; always work through the paper and apply pressure along veins, which are the structural supports of the wing.

The standard positioning for a mounted butterfly is with the trailing edge of the forewings perpendicular to the body, or close to it. The hindwings tuck slightly under the forewings with a small overlap. Symmetry matters more than any rigid rule about angles: both sides should mirror each other. Once everything looks right, pin the paper strips firmly in place so nothing can shift during drying.

Drying and Curing

Leave the spread butterfly on the board in a dry, well-ventilated area out of direct sunlight for at least five to seven days. Larger tropical species with thick, fleshy bodies may need two weeks. The goal is for all moisture to leave the body and wings so the specimen becomes rigid in the posed position. Rushing this step by using heat or placing the board in direct sun tends to cause the abdomen to shrink unevenly or the colors to fade.

You know the butterfly is ready when the body feels completely hard and the wings hold their position without any support. Carefully remove the paper strips and any secondary pins, then lift the butterfly by its main pin. It should feel stiff and light. If the abdomen still gives slightly when pressed, give it a few more days.

Display Options

Once dried, the butterfly needs a sealed environment. Exposure to open air invites dust, humidity swings, and the pests that will eventually destroy it. There are several common approaches, each with trade-offs.

Riker mounts: Shallow cotton-filled boxes with glass tops. The butterfly rests on the cotton without a pin, held in place by the glass lid pressing gently on it. These are inexpensive and look clean, but they flatten the body and can compress delicate structures over time.
Shadow boxes and display cases: Deeper frames with a pinning surface on the back. The butterfly stays on its pin, preserving the three-dimensional shape of the body and antennae. These give the most natural appearance and are what most serious collectors use for wall display.
Drawer units: Standard museum storage uses shallow wooden drawers with foam or cork bottoms, lined in rows. These are meant for study collections rather than display, and they stack in cabinets with tight-fitting lids to keep pests out.

Whichever display method you choose, keep the specimen out of direct sunlight. Ultraviolet light degrades the pigments and structural colors on butterfly wings over months to years, turning vivid blues and greens into dull browns. A spot on an interior wall away from windows is ideal. If you want to use a well-lit area, UV-filtering glass or acrylic in the frame helps considerably.

The Biggest Long-Term Threat Is Not Humidity, It Is Beetles

The number-one destroyer of preserved insect collections is not moisture, mold, or sunlight. It is other insects, specifically carpet beetles in the family Dermestidae. The varied carpet beetle, Anthrenus verbasci, is the most common culprit. Its tiny larvae feed on dried animal protein, which includes the chitin, scales, and body tissues of your mounted butterfly. Museum professionals consider carpet beetles responsible for the complete loss of insect specimens in collections around the world, and the larvae can squeeze through remarkably small cracks to reach supposedly sealed drawers.

You will know you have a carpet beetle problem when you find fine powdery dust beneath your specimens and tiny shed larval skins nearby. By that point, the damage is already done to whatever they have been feeding on. Prevention is the only reliable strategy for home collectors.

The simplest preventive measure is to include a pest strip or mothball (paradichlorobenzene, not naphthalene, which can damage some specimens) inside your sealed display case or storage drawer. Check specimens every few months for signs of frass or tiny holes. Some collectors freeze their entire collection periodically, placing sealed drawers in a chest freezer for a week to kill any larvae that may have found their way in. Museum-scale operations have explored more aggressive approaches, including gamma radiation treatments to sterilize or kill carpet beetle larvae at various life stages.² For a home collection, tight-sealing cases and periodic freezing are more practical and get the job done.

Handling Grease and Discoloration

Some butterflies, particularly large-bodied species like swallowtails and silk moths, develop grease spots on the wings weeks or months after mounting. This happens because lipids in the body slowly migrate through the wing veins and wick into the membrane. The result is a translucent, oily-looking patch that darkens over time and can permanently stain the wing.

To prevent greasing, some collectors remove the abdomen before mounting, replace it with a small cotton plug shaped to mimic the body, and store the original abdomen separately in a small vial of alcohol (useful if the specimen ever needs to be identified by its genitalia, which is common in lepidopteran taxonomy). This sounds drastic, but it is standard practice for species prone to greasing, and it keeps the wings pristine for decades.

If grease spots have already appeared, the traditional remedy is to soak the affected wings in a solvent like xylene or acetone. This requires removing the butterfly from its pin, carefully submerging the wings, and re-spreading it after cleaning. The process works but carries real risk of damaging the specimen if you are inexperienced, and the solvents involved are toxic and require good ventilation.

Safety Concerns With Older Collections

If you have inherited or purchased a vintage butterfly collection, be aware that specimens preserved before the late twentieth century were often treated with chemicals now recognized as serious health hazards. Arsenic and mercury compounds were widely used as pest deterrents in natural history collections for over a century. Organochlorine pesticides like DDT and lindane were also applied directly to storage cases and specimens. These substances do not disappear over time; they persist in the specimens and in the dust that accumulates inside old drawers and cases.

A study at a major natural history museum found measurable levels of arsenic, mercury, and organochlorine pesticides in both the settled dust and the ambient air of rooms housing historical collections. These compounds are classified as carcinogenic and mutagenic, posing a real health risk to anyone who regularly handles contaminated objects without protection. If you are working with old specimens, wear nitrile gloves and avoid breathing dust from the cases. Washing your hands after handling is not optional. For large inherited collections, it may be worth having a representative sample tested, especially if you plan to store them in living spaces.

Preserving for Science, Not Just Display

A well-preserved butterfly is more than a decorative object. Museum specimens pinned decades or even centuries ago are now yielding DNA for genetic research, allowing scientists to track how populations have changed over time. Recent techniques allow researchers to extract historical DNA from pinned Lepidoptera specimens with minimal physical damage to the specimen itself. These DNA libraries show characteristic damage patterns consistent with aged genetic material, confirming their authenticity, and the extracted DNA is good enough for genomic studies that track population genetics, species boundaries, and responses to environmental change.⁴

This has practical implications for how you preserve your specimens. If there is any chance your collection could have scientific value, whether because you collected in an area that has since been developed, or because you have unusual species, or simply because your records are detailed, certain practices protect that genetic potential. Keeping the specimen dry and out of extreme heat slows DNA degradation. Avoiding chemical treatments like formaldehyde, which cross-links and damages DNA, preserves it better than aggressive pest treatments. Labeling each specimen with a date, location, and collector name transforms it from a pretty object into a scientific data point. Even a modest home collection, if well-documented and properly stored, can contribute to research decades from now.

Common Beginner Mistakes

Most first attempts at butterfly preservation go wrong in predictable ways. Knowing where people typically fail helps you skip the learning curve.

Using regular pins: Sewing pins are too short, too thick, and they rust. Rust stains spread through the body and can corrode the specimen from the inside out. Entomological pins are specifically designed for this.
Spreading on a flat surface without a groove: If the body is not cradled in a channel, the wings will dry at an upward angle rather than flat. Once dried, there is no fixing the position without relaxing the entire specimen and starting over.
Removing the butterfly from the spreading board too early: Impatience is the most common error. If the body is not fully cured, the wings will slowly droop after removal, and you will end up with a butterfly whose wings sag below horizontal. When in doubt, give it more time.
Touching wing surfaces directly: The colors on butterfly wings come from tiny overlapping scales. Every touch transfers scales to your fingers, leaving bald patches that cannot be repaired. Always handle by the body or thorax, and use paper strips and tools rather than fingertips when working with the wings.
Sealing in a non-airtight frame: A beautiful shadow box with a loose-fitting back is an invitation for carpet beetle larvae. If you can see daylight through the edges when you hold the frame up to a light, pests can get in.

Resin Embedding as an Alternative

Some people prefer to embed butterflies in clear resin rather than pin and frame them. This produces a solid, handled-friendly block with the butterfly visible from all sides, essentially a permanent paperweight. The specimen is completely sealed from air, moisture, and pests, which eliminates all long-term storage concerns in one step.

The trade-off is that embedding is irreversible. Once the butterfly is in resin, it cannot be repositioned, re-spread, or examined from different angles under a microscope. Any DNA in the specimen is locked away and potentially degraded by the curing chemicals. For a decorative keepsake, resin works well. For anything with potential scientific or collectible value, traditional pinning remains the standard because it keeps options open.

The process itself requires careful technique. Pouring resin generates heat as it cures, and too-thick layers can produce enough heat to discolor the specimen or create bubbles. Most successful resin embeddings are done in thin successive layers, letting each one partially cure before adding the next, which can take several days. Using a slow-cure, low-exotherm resin formulated for embedding biological specimens gives better results than general-purpose craft resin.