5 Things Worth Knowing About Superworms Before You Feed Them

I've kept superworms in a bin in my garage for years, and most of what people repeat about them is half-right at best. They get lumped in with mealworms, called a "fatty junk food," and stuck in the fridge where they promptly die. So before you toss a handful into your dragon's bowl, here are five things about Zophobas morio that actually change how you keep and feed them.

1. They're darkling beetle larvae, not giant mealworms

Superworms (Zophobas morio) and mealworms (Tenebrio molitor) are both larvae of darkling beetles, but they're different species with different care. A grown superworm runs 1.5 to 2 inches, with a soft, segmented body and a thinner cuticle than people expect. They're native to Central and South America and in the wild they feed on decaying plant matter and organic debris.

The practical difference is behavior and hardiness. Superworms are active, exploratory, and surprisingly strong for their size. They don't enter a dormant state on demand the way mealworms do, which matters a lot for storage, covered next.

2. They store at ROOM temperature — the fridge kills them

This is the single most common mistake I see. Mealworms can be refrigerated to slow them down and stretch their shelf life. Do not do this with superworms. Cold is lethal to them. Held below roughly 60°F, superworms get sluggish, sicken, and die off within a few days.

Keep them at room temperature, ideally 70-80°F, in a ventilated container with an inch or two of wheat bran or rolled oats as both bedding and food. Toss in a slice of carrot, potato, or apple a couple times a week for moisture, and pull it before it molds. Kept this way they'll hold for weeks without any special equipment. I cover the full setup, including why this differs from mealworms, in my guide to storing feeder insects.

3. They're energy-dense — great fuel, easy to overdo

Superworms are genuinely high in fat, which is exactly why animals go crazy for them and why they're useful for underweight, breeding, or recovering reptiles that need calories. That same fat is why they're a rotation feeder rather than an everyday staple for an otherwise healthy adult.

In my rotation, superworms show up a few times a week as a high-value item, balanced against leaner feeders. For an active, growing, or skinny animal I lean on them more; for a sedentary adult dragon I pull back to avoid a fat, lazy lizard. Variety is the real goal, and superworms are one strong note in the chord, not the whole song.

4. The calcium catch: they're phosphorus-heavy

Here's the nutrition reality the marketing copy skips: superworms have very little calcium and a lot of phosphorus, so their natural calcium-to-phosphorus ratio is unfavorable. Reptiles need more calcium than phosphorus to keep their bones and metabolism healthy, so feeding straight superworms long-term invites metabolic bone disease.

The fix is two-step and easy. First, gut-load the superworms for a day or two before feeding on calcium-rich greens and quality feeder chow so the worm itself carries better nutrition. Second, dust them with a calcium (and periodically calcium-plus-D3) supplement right before they go in the bowl. The Merck Veterinary Manual's reptile nutrition guidance is blunt about this: most feeder insects need supplementation to deliver an appropriate calcium balance (MSD/Merck Vet Manual). If you want the full routine, see my feeder gut-loading guide.

5. They can digest plastic — but that's a lab fact, not a feeding tip

You'll see headlines that superworms "eat plastic." It's real: researchers at the University of Queensland documented Zophobas morio larvae surviving on polystyrene, with gut bacteria producing enzymes that break the polymer down (Univ. of Queensland study summary). It's a fascinating glimpse of bioremediation potential.

It is not a care instruction. Worms raised on polystyrene are stressed and poorly nourished. You want feeders raised on clean grain and produce, because what the worm eats becomes what your reptile eats. The plastic story is a reason to find superworms interesting, not a reason to change their diet.

Where superworms fit, and where to get them

Used right, superworms are one of the most useful feeders in the rotation: high-value, easy to keep, no refrigerator required, and a reliable calorie boost when an animal needs it. The whole game is moderation plus supplementation. If you want to compare them head-to-head with their smaller cousin, I broke that down in mealworms vs superworms. When you're ready to stock up, I get mine as live superworms from All Angles Creatures.

For more feeder fundamentals, see my complete feeder insect ranking for 2026 and the keeper's hub of care guides.