A review of adhesives for entomotaxy

Insect specimens that are too small to be pinned safely are usually affixed to a piece of card on a pin or to the pin itself using an adhesive. This practice has been in place for more than two centuries, and >400,000 such mounts continue to be accessioned annually in collections. Entomologists appear to agree on the ideal properties of adhesives used in specimen preparation---that they remain (1) archival, (2) reversible, (3) easy to prepare and use, and (4) safe. There remains no consensus, however, regarding which adhesives satisfy these criteria. Entomologists continue to use fixatives they were taught to use (institutional inertia) or which have good initial working properties, even though their archivability and reversibility have never been tested or have been shown to be suspect. Museum professionals recently identified this topic, adhesives applied to natural history specimens, as one that could be informed by research and knowledge from other domains. This review includes a comprehensive list of adhesives used in entomotaxy, with brief summaries of their properties as examined in the contexts of archaeology, paleontology, art restoration, and polymer chemistry. The general conclusion is that no adhesive has the properties sought by entomologists, and several commonly used brands or classes of adhesive should never be used for entomotaxy, including most clear nail polishes, shellac, and certain polyvinyl acetate-based dispersions, like Elmer's Glue-All.