How To Pin Dragonfly Specimens: A Complete Entomological Guide

Pinning a dragonfly requires precise positioning, rapid post-mortem handling to prevent decomposition and color fading, and delicate use of specialized entomological tools to preserve the specimen's structural integrity. Mastering this technique ensures your Odonata specimens remain stable, display natural wing posture, and maintain long-term scientific value for academic or amateur collections.

Essential Gear, Environment, and Specimen Preparation

Preparing to pin odonates requires careful organization of specialized entomological supplies. Unlike beetles or butterflies, dragonflies possess unique biological challenges: their vibrant colors (especially blues, reds, and greens) tend to fade post-mortem due to post-mortem lipid degradation and gut content decomposition, and their bodies dry out rapidly, becoming extremely brittle.

Before handling any specimens, gather the necessary equipment and establish a clean, stable workspace. Work in a well-lit area with a binocular microscope or magnifying lamp if available, as precision is paramount when aligning fragile body parts.

• Essential Tools and Materials: Entomological pins (sizes #2 through #4 stainless steel), a high-density pinning block (foam or plastazote), a relaxing chamber (airtight container with damp paper towels and a few drops of thymol or carbolic acid to prevent mold), standard fine-tipped stainless-steel forceps, glassine paper or translucent parchment strips, a pinning board or adjustable spreading board with a center groove, and pure acetone or ethyl acetate for immediate abdominal clearing if necessary.
• Prerequisite Standards: Specimens must be fresh (ideally pinned within hours of collection) or completely relaxed. Never attempt to pin a stiff dragonfly without relaxing it first, as the thorax and abdomen will shatter under pressure.
• Project Duration and Investment: Relaxing a dried specimen takes 24 to 48 hours. Active pinning and setting require approximately 30 to 45 minutes per specimen, followed by a drying period of 10 to 14 days in a controlled, low-humidity environment.

Step-by-Step Odonata Pinning and Spreading Workflow

Step 1: Relaxing and Softening Dry Specimens

If your dragonfly is already dry and rigid, you must relax it before applying any pins. Place a damp paper towel at the bottom of an airtight plastic container. Add a few crystals of thymol to inhibit fungal growth during the process. Place the dragonfly on a small platform inside the container above the direct moisture, seal the lid, and let it sit for 24 to 48 hours.

Warning: Never submerge a dragonfly specimen directly in water to relax it, as this ruins cellular structure, strips delicate hairs, and causes catastrophic scale or pigment loss.

Step 2: Selecting and Inserting the Primary Pin

Select a stainless-steel entomological pin of appropriate gauge—typically a #3 or #4 pin for larger dragonflies like darners and cruisers, and a #2 pin for smaller damselflies or clubtails. Hold the dragonfly gently across the sides of its thorax using fine forceps. Insert the pin vertically downward through the right side of the mesothorax, slightly posterior to the base of the forewings.

Pro-Tip: Ensure the pin exits cleanly between the middle and hind legs on the ventral side without displacing the coxae. The pin must remain perfectly perpendicular to the longitudinal axis of the body, as a crooked pin ruins the alignment in the display drawer.

Step 3: Mounting on the Setting Board

Push the pinned dragonfly into the center groove of your spreading board until the ventral surface of the thorax rests lightly against the board's center line. The wings should be level with or slightly above the dual wings of the board surface. Adjust the height of the pin so that the underside of the thorax clears the board by roughly 8 to 10 millimeters, leaving ample room below for the future placement of locality and identification data labels.

Step 4: Positioning and Securing the Wings

Using fine-tipped forceps, gently lift the forewing on one side and move it forward until the trailing edge of the forewing forms a straight line perpendicular to the body, or angles slightly forward. Anchor the wing temporarily by pinning through the wing membrane in the costal space near the base, taking care never to pierce the major veins. Repeat this process for the hind wing, sliding it slightly forward so the anterior margin of the hind wing rests just beneath the posterior margin of the forewing. Repeat the procedure symmetrically for the left wings.

Step 5: Securing the Abdomen and Antennae

Dragonfly abdomens have a tendency to sag, curl, or break as they dry due to internal muscle contraction. Support the abdomen horizontally by placing crossed pins underneath it at regular intervals along its length, or by resting it inside a temporary paper support trough made from folded cardstock. Ensure the head is straight and the antennae are gently aligned backward against the frons.

Entomological Equipment Comparison for Odonata Preservation

Common Specimen Failures and Field Fixes

Even experienced preparators encounter structural setbacks during the pinning and drying phases. Recognizing the root cause of these failures allows for immediate intervention and salvaging of valuable specimens.

• Symptom: Abdomen collapses, shrivels, or turns black.
  
  
  • Root Cause: Gut contents decomposing inside the hollow abdominal cavity before bodily fluids can evaporate, causing lipid oxidation and tissue rot.
  • Actionable Fix: Remove the entrails through a small ventral incision near the terminal segments using micro-scissors, flush the internal cavity with pure acetone using a fine glass pipette, and stuff the abdomen loosely with cotton thread before pinning.
• Symptom: Wings spring back out of position after removing glassine strips.
  
  
  • Root Cause: The specimen was removed from the spreading board prematurely before the chitinous wing hinges fully cured in their new position.
  • Actionable Fix: Rehydrate the wing bases in a relaxing chamber for 2 to 4 hours, reposition them on the spreading board, and leave them to dry for an additional week.
• Symptom: The pin rotates or spins freely within the soft thorax tissue.
  
  
  • Root Cause: Using an overly thick pin for a small specimen, or the thorax tissues were not adequately dried, causing internal slippage.
  • Actionable Fix: Apply a microscopic drop of clear polyvinyl acetate (PVA) adhesive or clear nail polish to the point where the pin enters the dorsal thorax, then let it set vertically.

Frequently Asked Questions

How long does a pinned dragonfly take to dry completely?

A standard dragonfly specimen requires a minimum of 10 to 14 days to dry completely in a climate-controlled room with low relative humidity (under 40%). Larger species with robust thoraxes and thick abdomens may require up to three weeks. Always verify dryness by gently testing the flexibility of the abdomen before removing support pins.

Should I remove the internal organs of a dragonfly before pinning?

For large aeshnids (darners) and gomphids (clubtails), evisceration is strongly recommended to prevent post-mortem abdominal blackening and grease seepage. Smaller species like damselflies and skimmers generally dry quickly enough on their own without requiring manual gut extraction.

Can I pin a dragonfly that has been stored frozen?

Yes, freezing is an excellent method for temporarily storing freshly caught specimens until you have time to pin them. Thaw the specimens gradually inside a sealed container placed in a refrigerator for several hours to prevent condensation damage, then pin them immediately while they are pliable.

How do I prevent post-mortem color fading in bright blue dragonflies?

The bright pruinescent blues and greens found in many odonates are caused by microscopic waxy layers or structural pigments that degrade when exposed to moisture and fats post-mortem. While complete preservation is challenging, injecting the abdomen with acetone immediately after capture helps dissolve fats and preserves structural coloration more effectively.

Elevate your entomological collection standards by mastering precise pinning workflows and utilizing professional-grade preservation materials. Explore our advanced resources on taxonomic identification and cabinet curation to safeguard your scientific specimens for decades.