Superworm Nutrition Guide

A high-energy feeder larva.

Superworms (Zophobas morio) are the larvae of a darkling beetle and are widely used as live feeders for reptiles, amphibians and other insectivorous animals.

They are sometimes confused with oversized mealworms, but superworms are a different species with their own nutritional profile. Research consistently characterizes Zophobas morio larvae as an energy-dense feeder with substantial protein and particularly high fat content.

Like other feeder insects, however, a superworm does not have one immutable nutritional composition. Diet, rearing conditions, developmental stage and laboratory methodology can influence the values measured.

Superworm nutrition at a glance

For the primary numbers on our nutrition guide, we use Mark Finke's 2002 analysis of commercially raised Zophobas morio larvae. Unlike our banded-cricket data, these values were reported as-fed, so they describe the insects with their naturally occurring moisture included.

Why these are as-fed values

“As-fed” means the water contained in the live insect remains part of the calculation.

That distinction matters. Superworm larvae in Finke's analysis were 57.9% moisture, meaning only about 42.1% of their live weight was dry matter. A protein percentage reported on a dry-matter basis will therefore look dramatically higher than the protein percentage of the same insect expressed as-fed.

We don't mix the two bases when presenting nutrition data.

Why we don't publish a different nutrition number for every superworm size

Our Small, Medium and Large superworms are commercial size grades — not three separately analyzed species or nutritional categories.

Published research shows variation in Zophobas morio composition, but it does not provide reliable nutritional analyses corresponding to each of our retail size grades.

A major review of published Zophobas morio research found larval dry matter ranging from 35.2–42.1%, crude fat from 35.0–43.6% DM, ash from 2.4–8.2% DM, and ADF from approximately 6.3–6.5% DM.

That is why we publish a well-documented species-level analysis rather than inventing different nutrition numbers for Small, Medium and Large superworms.

Source: Rumbos CI and Athanassiou CG, 2021. The Superworm, Zophobas morio (Coleoptera: Tenebrionidae): A ‘Sleeping Giant’ in Nutrient Sources. Journal of Insect Science 21(2):13. Values reported on a dry-matter basis.

Superworms are particularly high in fat

This is one of the biggest nutritional differences worth understanding.

Finke's live, as-fed analysis measured superworms at 17.7% crude fat. On a dry-matter basis, the broader scientific literature places superworm larval fat at approximately 35.0–43.6% DM.

That makes superworms an energy-dense feeder.

It doesn't make them “bad” feeders. It means their nutritional characteristics should be considered when deciding how frequently they're offered and how they fit alongside other feeder insects.

The calcium problem

Like many commonly used feeder insects, superworms naturally contain substantially more phosphorus than calcium.

A review of published Zophobas morio analyses found approximately:

In other words, the ratio is strongly phosphorus-heavy.

Superworms therefore should not be described as naturally calcium-balanced feeders.

What a superworm eats can change what it delivers

This isn't merely theoretical.

A controlled study involving 2,000 Zophobas morio larvae tested different feeding substrates and feeding periods. Researchers found significant changes in calcium, phosphorus and metabolizable energy depending upon what the larvae had been fed.

Most notably, feeding a high-calcium cricket diet substantially increased the calcium content and improved the Ca:P ratio of the larvae.

That's useful evidence for the principle behind gut loading: feeder nutrition can be influenced by feeder diet.

Source: Latney LV, Toddes BD and Wyre NR, 2017. Effects of various diets on the calcium and phosphorus composition of mealworms (Tenebrio molitor larvae) and superworms (Zophobas morio larvae). PubMed ID 28140633.

What about dusting?

Gut loading and dusting aren't the same thing.

Gut loading involves feeding the insect an intentionally selected diet before it is offered to an animal.

Dusting applies a powdered supplement externally shortly before feeding.

Because untreated superworms naturally have a strongly phosphorus-heavy calcium-to-phosphorus balance, their protein and energy content shouldn't be interpreted as eliminating the need to consider calcium and other supplementation within the animal's overall feeding program.

Superworms vs. mealworms

They're related darkling-beetle larvae, but they aren't nutritionally interchangeable.

In Finke's directly comparable as-fed analysis:

The clearest difference is fat: the analyzed superworms contained substantially more fat than the mealworms.

Where superworms fit

Superworms can provide protein, fat and energy as part of a varied insectivore diet.

Their larger size and substantial energy density make them useful feeders for appropriately sized animals, but feeder size should always be matched to the animal being fed.

Variety still matters. No individual feeder insect provides an ideal nutritional profile for every animal or every feeding situation.

Explore: Mealworm Nutrition Guide · Feeder Size Guide · Gut Loading Feeder Insects