Superworms' help scientists with a vexing task: Cleaning animal specimens

Superworms' help scientists with a vexing task: Cleaning animal specimens

Museum curators and researchers frequently face a difficult dilemma: the need for perfectly cleaned skeletal specimens for education and scientific study versus the risk of destroying fragile bones during the cleaning process. A new study published July 1, 2026, in the journal PLOS One suggests a practical solution using the larvae of Zophobas morio, commonly known as superworms.

The research, conducted by a team including scientists from the Ferdowsi University of Mashhad in Iran and the State Museum of Natural History in Stuttgart, Germany, identifies these commercially available beetle larvae as an efficient, museum-safe alternative to traditional skeletal preparation.

The Problem with Traditional Cleaning

Natural history museums often receive a wide variety of donations, including animals that died in the road or injured birds. To study or exhibit these as skeletons, the flesh must be removed. According to Niloofar Alaei Kakhki, a bioinformatician and co-author of the study, existing methods each carry significant drawbacks:

• Chemical treatments can degrade skeletons and are often harmful to the environment.
• Boiling is time-consuming and can damage "tiny, delicate bones."
• Dermestid beetles are efficient but pose a severe risk to museum collections; if they escape, they can destroy preserved specimens by chewing through dried skin and feathers.

The researchers demonstrated these failures by cleaning a Marbled Polecat using the conventional boiling method for 90 minutes followed by manual dissection. The process warped delicate rib elements and loosened teeth, making them difficult to reseat correctly.

The Superworm Advantage

Superworms, which are native to Central and South America and widely sold as pet food, offer several biological advantages over dermestid beetles. While dermestid colonies involve multiple life stages, superworm cleaning relies solely on the larval stage. Crucially, superworms do not pupate under crowded conditions, which significantly reduces the risk of adult beetles emerging and escaping into the museum.

Their larval feeding phase also lasts 10 to 12 weeks, compared to the five to seven weeks typical of dermestid beetles.

Methodology and Results

The team tested the larvae on eight different species, ranging from a 9-gram Egyptian rousette bat to a 4-kilogram gray wolf. The process began with skinning and the removal of internal organs. For medium and large specimens, the team softened tissues in hot water at 80°C to assist in the removal of fats and muscle.

Because larger animals did not fit in single containers, the gray wolf was divided among four containers and the wild cat among three. To maintain efficiency, the researchers rotated specimens every six to eight hours into fresh containers of larvae that had been starved for 24 hours.

The study identified a critical "sweet spot" for the larva-to-specimen ratio. The researchers found that a ratio of 10 to 15 grams of larvae per gram of animal specimen provided the best balance. This ratio minimized cleaning time while preventing bone damage. In contrast, very high ratios led the worms to gnaw on thin cranial and rib bones in the smallest specimens, while too few larvae caused the cleaning process to drag on, allowing tissues to harden.

The larvae successfully cleaned internal cavities that are typically difficult to reach and managed to clear a fish skeleton without compromising its "super, super tiny" ribs.

Maintenance and Limitations

Maintaining a superworm colony is straightforward, requiring temperatures between 25-28°C and relative humidity of 60-70%. However, the researchers noted that superworms are primarily herbivorous. While they can digest animal tissue, prolonged feeding on flesh may increase mortality rates or disrupt molting. To ensure the larvae can be reused for nearly six months, the team recommends supplementing their diet with fruit or vegetable peels after each cleaning session.

Not all experts are entirely convinced. Damien Charabidze, a forensic entomologist at the University of Lille, expressed concern that the worms' powerful mandibles could inadvertently snap small bones and noted that the worms might be finicky feeders since cadavers are not their usual food. Similarly, Marna Sakalem, an anatomist at the State University of Londrina, stated that her team has not observed dermestid beetle escapees in five years of work and is not yet ready to abandon traditional methods.

The researchers conclude that superworms provide an adaptable, environmentally friendly, and inexpensive option, particularly for smaller institutions without advanced insect facilities.