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Superworms: The Bigger, Brawnier, Hungrier Cousins of Yellow Mealworms

Zophobas morio larvae

Larvae of the darkling beetle species Zophobas morio have earned the nickname “superworms” for their larger size and increased nutritional potential as food and feed compared to yellow mealworms. And yet less research and regulatory consideration has focused on Z. morio, something a pair of researchers in Greece hope to change. (Photo by Christos I. Rumbos, Ph.D.)

By Ed Ricciuti

Ed Ricciuti

Ed Ricciuti

Look out, yellow mealworm—you have competition. A bigger, brawnier cousin could threaten your position as a go-to food for backyard bluebirds, pet parrots and lizards, and even tree shrews in zoos, as well as a potential protein source for people, farmed fish, and livestock. Even your reputation as top trout bait could be threatened.

So say Greek scientists who reviewed research on Zophobas morio, the so-called “giant mealworm” or “superworm,” in a paper published in April in the open-access Journal of Insect Science. They deem Z. morio to be “a well-promising insect-based protein source,” whose potential still remains to be seen. However, there is even more to it than that. This species also shows promise for use in animal health and coping with the world’s plastic waste problem. The look at Z. morio is part of a new special collection in the Journal of Insect Science, titled “Insects as Food and Feed: If You Can’t Beat Them, Eat Them!

A caveat about nomenclature is required here. “The term ‘giant mealworm’ is used also to describe juvenile hormone–treated larvae of the yellow mealworm (Tenebrio molitor),” says Christos I. Rumbos, Ph.D, who authored the paper with Christos G. Athanassiou, Ph.D., both of the University of Thessaly in Volos, Greece. The hormone prevents the yellow mealworm from pupating, and thus prolongs growth. In the case of Z. morio, pupation can be delayed merely by overcrowding. Both mealworms are larvae of different darkling beetles (Tenebrionidae). Zophobas morio adults measure up to 57 millimeters long, while T. molitor is virtually a black speck by comparison at only 12 to 25 millimeters.

Zophobas morio is consumed by humans in some countries, such as Mexico and Thailand. Superworms are also sold extensively by pet stores as treats for lizards and some birds. The authors, however, believe superworms deserve much more attention.

“The aim of this paper is to highlight the significance of a usually overlooked insect species,” says Rumbos. “Although a tremendous amount of research is directed to the relative species Tenebrio molitor (yellow mealworm), Z. morio has not attracted so far the attention that we think it deserves, not only in terms of research but also from the regulatory authorities.”

Special Collection: Insects as Food and Feed

“Some ‘pests’ may not be ‘pests’ after all, but highly beneficial agents for human nutrition.” Find out why in the new special collection, “Insects as Food and Feed: If You Can’t Beat Them, Eat Them!” in the open-access Journal of Insect Science.

Just this January, the European Union declared yellow mealworms as safe for human consumption. The authors stress that the rules governing the use of insect-based products for food must be adjusted to include the superworm for it to realize its potential.

After their extensive review, Rumbos and Athanassiou opine that recent studies “show that Z. morio can be a valuable nutrient and antimicrobial source that could be utilized further in insect-based feed and food production.” Feeding trials, they say, have shown that the superworm has great promise in aquaculture, “both in terms of fish development and health.” Other research suggests that it has comparable value to other insects for feeding poultry.

Studies cited by the authors show that superworms are rich in nitrogen, fatty acids, and amino acids that are the building blocks of protein and energy-producing omega-6 linoleic acid. And that’s just for starters: Superworms also seem to promote the growth of probiotic bacteria and thus help shield against pathogens.

Zophobas morio larvae are a valuable, largely unexploited source of antimicrobialpeptides with antiradical activity; therefore, their consumption could potentiallyhave an immune-triggering and health-promoting effect,” write the authors. The superworm might provide an alternative to the use of antibiotics to keep chickens farmed for meat disease-free.

Other research has shown that Z. morio hemolymph, the insect equivalent of blood, can effectively protect mammary epithelial cells of cattle against bacterial infections, suggesting its potential to fight bovine mastitis, the most prevalent disease affecting the dairy industry worldwide. “The spectrum of Z. morio applications,” the authors conclude, “is continuously growing.”

A huge bonus that comes with using mealworms of either species as animal feed is that the worms themselves are living waste eliminators, capable of eating, biodegrading, and mineralizing various types of plastics, such as polystyrene or polyethylene. In effect, they can nosh on Styrofoam cups and still be safe to feed animals. In fact, research reported last year demonstrated that Z. morio consumes plastic foam at a rate four times higher than does the yellow mealworm.

“These new findings,” say the authors, “are of high importance for plastic waste management and could offer a reliable solution to the problem of plastic accumulation, which represents a global issue of major environmental importance. … Further research is needed to fully unfold the potential applications of this species and optimize its farming systems at an industrial scale.”

Ed Ricciuti is a journalist, author, and naturalist who has been writing for more than a half century. His latest book is called Bears in the Backyard: Big Animals, Sprawling Suburbs, and the New Urban Jungle (Countryman Press, June 2014). His assignments have taken him around the world. He specializes in nature, science, conservation issues, and law enforcement. A former curator at the New York Zoological Society, and now at the Wildlife Conservation Society, he may be the only man ever bitten by a coatimundi on Manhattan’s 57th Street.


  1. I have been raising Z Moria for 15 + years as reptile food, up to 450k a week. There have been several issues lately in the USA with them dying off at all larvea stages. One issue is spinning as if theyvare unable to molt, and then they die. Would you have any insight on this perplexing situation?

  2. Qrrs with nutritional things they cant get their pets to otherwise eat by feeding it to the worms just before they give them to their pet for just that reason.
    Theyve also neglecting to mention Yellow Mealworms skin ‘problem’. Its made of Chitin. An undigestible material that in some animals, especially smaller pet and wild seed and insectivorous birds, can cause blockages that will kill them. One weekend I lost two great birds because one family member did not check with another before feeding two healthy (vet cared for) pet birds their daily ration on two days in a row of less than 8 small, (not Super!), Yellow Mealworms! The necropsy on both showed the impaction was the mealworms. If you have a pet that eats the insides only, like hes squeezing toothpaste out if a tube, you probably have much less to worry about but dont let what happened to me… What I was responsible for happen to you.You cant bring these beautiful creatures back!
    I think they better look at the people that have been eating these in quantity for years. I know in African communities theyre consumed more commioly but they also are more hesitant to see a physician unless they are deathly ill.

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