Silkworms vs Mealworms: Which Feeder Is Actually Better?
I've kept silkworms and mealworms side by side in my feeder fridge and bins for years, and the two are not interchangeable. They sit at opposite ends of the feeder spectrum: one is a soft, lean, water-rich worm, the other is a hard-shelled, fatty, shelf-stable backup. Picking the right one comes down to who you are feeding and why.
The Quick Verdict
For most reptiles most of the time, silkworms are the better feeder on nutrition and safety. Mealworms keep a place in the rotation for budget, convenience, and the occasional protein bump for adults. Here is how they stack up on every metric that actually matters.
| Category | Silkworms | Mealworms | Edge |
|---|---|---|---|
| Fat | ~1% | ~13% | Silkworms (far leaner) |
| Moisture | ~83% | ~62% | Silkworms |
| Chitin (hard shell) | None | High, tougher with age | Silkworms (lower impaction risk) |
| Ca:P ratio | ~0.77:1 | ~0.04:1 | Silkworms (much better, still dust) |
| Protein | ~9% | ~20% | Mealworms |
| Safe for juveniles? | Yes, all ages | Adults only | Silkworms |
| Storage | Room temp, needs chow, ~1-2 weeks | Fridge, no feeding, weeks | Mealworms |
| Cost | Higher | Lower | Mealworms |
The Fat Gap: 1% vs 13%
This is the headline difference. At roughly 1% fat, silkworms are more than ten times leaner than mealworms at about 13%. For species that pack on fat easily, that gap is not academic. It is the slow difference between a lean animal and a chronically overweight one across months of feeding.
Leopard geckos store excess fat in their tails and armpits. Chameleons are notorious for gout and fatty liver disease when overfed rich insects. Adult bearded dragons go sedentary and heavy on a fatty diet. For all of these, a low-fat worm you can offer without guilt is genuinely useful.
The Chitin Problem
Mealworms have a hard chitin exoskeleton that gets tougher as the larva matures. Chitin is largely indigestible fiber, and in a young reptile with a developing gut it can contribute to impaction, especially if prey is sized too large. This is why most vets advise no mealworms for bearded dragons under about 6 months.
Silkworms have essentially no hard shell. They are soft-bodied through their whole larval stage, which is why I reach for them with hatchlings, recovering animals, and anything I'm worried about. Less mechanical stress on the gut, full stop.
The Calcium Reality (Read This Before You Skip Dusting)
Mealworms have one of the worst calcium-to-phosphorus ratios of any common feeder, around 0.04:1, meaning far more phosphorus than calcium. Excess phosphorus binds calcium, so an undusted mealworm-heavy diet quietly works against your reptile's calcium balance and bone health.
Silkworms at roughly 0.77:1 are dramatically better, but here is the honest part most marketing skips: that is still below the 1:1 to 2:1 ratio reptiles need, so silkworms are not a free pass. Dust silkworms with a plain calcium powder for most feedings. The one true exception in the feeder world is black soldier fly larvae, which are naturally calcium-rich and do not need dusting. If you want a no-dust calcium source in the rotation, that is the worm to add, not silkworms or mealworms.
For more on why phosphorus matters and how the calcium cycle works, the Merck Veterinary Manual's section on reptile nutrition and metabolic bone disease is a solid non-commercial reference: Merck Veterinary Manual — Nutrition of Reptiles.
Where Mealworms Actually Win
I don't dismiss mealworms. They earn their bin space:
- Cheaper. Dollar for dollar, mealworms are one of the most affordable feeders.
- Higher raw protein. Around 20% versus about 9% for silkworms, useful as an occasional protein bump for adults.
- Effortless storage. Toss them in the fridge and they hold for weeks with no feeding or cleaning. Silkworms are needier, room temperature plus mulberry-based chow, and a shorter usable window.
For a keeper on a budget who wants a low-maintenance backup feeder for an adult reptile, mealworms are a reasonable tool.
Best Use for Each
Silkworms: A premium low-fat variety feeder, roughly 2-3 times per week. Ideal for obesity-prone species, chameleons, picky eaters, juveniles, and animals recovering from illness. Dust with calcium. Browse sizes at All Angles Creatures silkworms.
Mealworms: An occasional supplement for adult reptiles only, 1-2 times per week at most. Convenient fridge storage. Always dust heavily with calcium. Skip entirely for juveniles under about 6 months.
The smartest diet leans on neither as a sole staple. Build around a protein backbone like discoid roaches, add BSFL for natural calcium, and use silkworms (and the occasional mealworm) for variety. If you keep roaches in the mix, my discoid roach keeping guide covers keeping that staple alive and breeding.
Sizing and Safety Recap
- Nothing wider than the space between your reptile's eyes. This is the single most reliable prey-size rule.
- Soft-bodied feeders (silkworms, BSFL, hornworms) are the safe choice for young or sensitive animals.
- Dust silkworms and mealworms with calcium. Do not dust BSFL.
- Variety beats any single "best" feeder. Rotate.
For exact portions, see my silkworm feeding chart and the full exotic-animals guide hub.