The skeleton of a wolf or bat you admire at the natural history museum may look pristine, but it wasn’t always that way — there’s a good chance flesh-eating beetles helped prepare those bones for display. For decades, many museums have relied on colonies of dermestid beetles to strip soft tissue, like skin and muscles, from skeletons. Unlike the harsh chemicals that would otherwise be used for bone preparation, these beetles can be gentler and clean hard-to-reach areas. But these colonies are a hassle to keep up, and escaped beetles can even be dangerous for valuable museum specimens that don’t need their skin removed.
Now, researchers may have found an even better biological cleanup crew.
In a new study published July 1 in the journal PLOS One, scientists found that superworms (Zophobas morio) — large beetle larvae commonly sold as pet food — can clean skeletons just as effectively while offering practical advantages. The larvae removed soft tissue from animals ranging from tiny bats to a 9-pound (4.2 kilograms) wolf without damaging even the most delicate bones.
Two of the paper’s authors, Niloofar Alaei Kakhki, a postdoctoral researcher at the State Museum of Natural History Stuttgart in Germany, and Morteza Monfared, a researcher at the Ferdowsi University of Mashhad in Iran, answered our questions via email about what makes superworms unique and how they could be used in laboratories and museums.
Kenna Hughes-Castleberry: Why are these critters called “superworms?” What makes them different from other beetle larvae?
Niloofar Alaei Kakhki and Morteza Monfared: Compared with the larvae of many other beetles, Zophobas morio larvae are much larger, which is one of the reasons they are so effective at removing soft tissue from bones.
What makes them truly unique, however, is their life cycle. Most beetle larvae pupate automatically once they reach the appropriate size. In contrast, superworms require an additional trigger: They must be isolated individually before they will pupate and develop into adult beetles. As long as they remain together in crowded conditions, they stay in the larval stage for several months.
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This characteristic provides a major advantage for skeleton preparation. Because the larvae remain larvae for an extended period, they can be used repeatedly for cleaning specimens without rapidly developing into adult beetles. After each cleaning cycle, they can simply be fed a vegetable-based diet, allowed to recover, and then used again.
This also makes them safer than beetles commonly used for skeleton preparation, such as Dermestes. Adult dermestid beetles can reproduce, and females may lay eggs on — or even inside — skeletal specimens. If eggs or larvae are accidentally introduced into museum collections, they can become a serious pest and damage valuable specimens. Since superworms do not develop into adults unless they are intentionally isolated, this risk is greatly reduced, making the method safer for museum collections.
A group of superworms in their larval stage.
(Image credit: Niloofar Alaei Kakhki and Morteza Monfared)
KHC: How did you figure out that the worms could clean the skeletons? Was that surprising?
NAK and MM: Several years ago, we started keeping a colony of Zophobas morio larvae (superworm) as live food for birds. As bird-watchers, we were often asked to help care for injured wild birds, so maintaining our own colony was more practical than purchasing larvae repeatedly. We fed the larvae mainly with vegetable scraps, such as cucumber, potato and banana peels.
One day, we ran out of vegetable waste. After lunch, we placed a leftover chicken bone with a small amount of meat still attached into the colony. To our surprise, the larvae gathered around it almost immediately and removed the remaining tissue with remarkable speed. Watching hundreds of larvae work together so efficiently was fascinating, and it immediately made us wonder whether they could be useful for something beyond animal feed.
At the same time, we were volunteering at the Zoology Museum of Ferdowsi University (ZMFUM), where preparing skeletal specimens was one of our regular responsibilities. We had experience with conventional preparation methods, including manual cleaning, boiling and burial. Although effective, these methods were often time-consuming and carried the risk of damaging delicate bones or losing small skeletal elements.
After observing how efficiently the larvae cleaned the chicken bone, we decided to test whether they could also prepare skeletal specimens. The first trials were remarkably successful. Within only a few hours, the larvae removed the soft tissues while leaving even delicate bones intact. Seeing the quality of the cleaned specimens was genuinely surprising and convinced us that this approach had real potential.
From that point on, whenever suitable animal specimens became available, we continued testing the method under different conditions, gradually refining it and optimizing the protocol. Over the following years, these observations evolved into the standardized, efficient and safe skeleton preparation method presented in our study. Yes, we were genuinely surprised. We already knew that superworms could consume a wide variety of organic materials, but we did not expect them to clean skeletons so quickly, so thoroughly, and with so little damage to even the most delicate bones.
A delicate bird skull after being cleaned by superworms.
(Image credit: Niloofar Alaei Kakhki and Morteza Monfared)
KHC: How do these superworms compare to other skeleton-cleaning products, like chemical cleaners? Are the worms better or worse at this task?
NAK and MM: Based on our experience, superworms offer several important advantages over existing skeleton preparation methods.
Compared with dermestid beetles, one of the biggest advantages is colony management. Because superworms only pupate when they are isolated individually, their life cycle can be controlled much more easily. As long as they are kept together, they remain as larvae and continue cleaning specimens. This greatly reduces the risk of accidentally introducing adult beetles or their eggs into museum collections, which is a major concern when working with dermestid beetles.
Compared with traditional methods such as boiling, manual cleaning or burial, the larvae also save a great deal of time and effort. Manual cleaning, especially for delicate specimens, can take many hours and always carries the risk of breaking or losing small bones. In contrast, the larvae can remove soft tissues efficiently while preserving even fragile skeletal elements.
Every preparation method has its own strengths and limitations, and the best choice depends on the type of specimen and the goals of the researcher. However, based on our experience using a wide range of preparation techniques, we believe that superworms provide an efficient, safe and practical alternative for many museum and research applications.
Rather than replacing every existing method, we see this technique as a valuable new tool that museums, universities and research laboratories can adopt and adapt according to their own needs.
A wolf skull being “cleaned” by superworms.
(Image credit: Niloofar Alaei Kakhki and Morteza Monfared)
KHC: On average, how much does it cost to use the worms?
NAK and MM: It is difficult to estimate an average cost because prices vary considerably between countries and suppliers. Rather than the initial purchase price, the long-term maintenance cost is what makes this method attractive.
A colony can be established from a relatively small number of superworms. Once the larvae reach the appropriate stage, a portion of them can be isolated to pupate and develop into adult beetles. These adults reproduce and generate new larvae, allowing the colony to become self-sustaining over time.
The equipment required is also quite simple. The colony can be maintained in plastic or glass containers with wheat bran as the bedding, at approximately 25 degrees Celsius [77 degrees Fahrenheit]. Between skeleton preparation cycles, the larvae can be fed inexpensive vegetable scraps, allowing them to recover before being used again. Larvae can remain in the larval stage for several months, meaning the same colony can be used repeatedly.
Another advantage is that the colony size can easily be adjusted to meet the needs of different users. A museum or laboratory processing a large number of specimens can maintain a larger colony, while smaller collections can operate with far fewer larvae.
Overall, we find the method is relatively inexpensive to establish and maintain, especially when compared with the time, labor and specialized facilities often required for traditional skeleton preparation methods.
KHC: Do you envision museums and laboratories implementing these superworm cleaners in the future? Why or why not? Is the cost worth it?
NAK and MM: We believe this method has the potential to be adopted by many museums, universities and research laboratories, particularly those that regularly prepare skeletal specimens.
One of its greatest advantages is that it combines efficiency, safety and relatively low operating costs. Compared with some traditional approaches, it requires only basic equipment and does not rely on expensive chemicals or specialized enzymatic treatments. This makes it especially attractive for smaller museums and institutions with limited resources.
We also see advantages in terms of colony management. Because the life cycle of superworms can be controlled, the risk of introducing damaging museum pests is much lower than with some other biological cleaning methods. At the same time, the larvae can be reused repeatedly over several months, making the system practical for long-term use.
Ultimately, whether this method is worthwhile depends on the needs of each institution. However, based on our experience, we believe it offers an excellent balance between cost, efficiency, safety and specimen quality. Perhaps one of the most rewarding aspects of this approach is that it works with a natural biological process rather than against it. Instead of relying on harsh treatments, the soft tissues become a food source that supports the growth of another organism, creating a sustainable cycle while producing clean skeletal specimens. We believe this is one of the most appealing aspects of the method.
A diagram showing how the worms could be implemented in skeleton preparations.
KHC: Are there any fun stories from your research you can share?
NAK and MM: We have collected quite a few memorable stories over the years!
One of the funniest happened while we were experimenting with burial as a skeleton preparation method. We buried the head of a Persian onager (Equus hemionus) on the university campus. Unfortunately, the specimen had already begun to decompose and had a very strong smell. Even after it was buried, we knew exactly where it was because that part of the campus still smelled terrible. We avoided walking past it whenever possible, but anyone who happened to pass by immediately noticed the odor. At one point, campus security even came over to ask what we were doing, probably wondering why we were digging a hole and burying something on university grounds!
Another memorable story involved our superworms colony itself. In the early days, we kept the larvae in our office at the Zoology Museum (ZMFUM). Almost everyone who entered the room was startled by the sight of thousands of large larvae constantly moving around in their containers. Many people kept their distance at first. But over time, as we explained their biology and demonstrated how useful they were for our research, people’s reactions changed. Some visitors even became genuinely interested in the colony, and a few who were initially afraid eventually asked to hold the larvae themselves.
Those moments reminded us that science is not only about experiments and data; it can also change the way people think about animals that are often misunderstood.
KHC: If there’s one thing you want our readers to take away from your work, what would it be?
NAK and MM: If there is one message we hope readers take away from our work, it is that nature often has far more to offer than we initially realize.
Many organisms are known for a single, well-established application. Zophobas morio, for example, is widely recognized as animal feed and, more recently, for its ability to consume certain plastics. Our work shows that the same species can also provide an entirely different and unexpected solution to a practical problem in museum science.
This reminds us that the first known application of an organism is not necessarily its most valuable one. Sometimes, its second or even third application can have an even greater impact. Discovering those possibilities begins with curiosity, careful observation and a willingness to ask new questions.
This interview has been edited for length and clarity.
