Silkworm Nutrition Facts: Why They're the Premium Feeder
- Role
- Rotation supplement
- Protein
- ~11%
- Fat
- ~2%
- Moisture
- ~80%
- Chitin
- very low
- Ca:P
- ~1:2
- Calcium-rich
- No (dust it)
- Best for
- Soft-bodied protein for picky or recovering animals
When experienced keepers and reptile veterinarians call silkworms (Bombyx mori) the "premium feeder insect," it isn't marketing — it's a nutritional profile no other common feeder can match. Silkworms sit in a niche all their own: ultra-low fat, no chitin, exceptional moisture, a comparatively decent calcium-to-phosphorus ratio, and one enzyme found in no other feeder. This guide breaks down the actual data and, just as importantly, what it means for how you feed.
The silkworm nutritional profile
| Nutrient | Value (per 100g, as-fed) |
|---|---|
| Protein | ~9% |
| Fat | ~1% |
| Fiber (chitin) | ~0% (no exoskeleton) |
| Moisture | ~83% |
| Calcium | ~34 mg/100g |
| Phosphorus | ~44 mg/100g |
| Ca:P ratio | ~0.77:1 |
Every line in that table earns the silkworm its reputation. Let's unpack the ones that drive feeding decisions.
Fat: just 1%
This is the headline. At about 1% fat as-fed, silkworms are the leanest feeder available by a wide margin. For comparison:
- Crickets: ~6% fat (6× more)
- Discoid roaches: ~7% fat (7× more)
- Mealworms: ~13% fat (13× more)
- Superworms: ~18% fat (18× more)
- Waxworms: ~25% fat (25× more)
For species prone to obesity — bearded dragons, leopard geckos, blue tongue skinks, and especially chameleons — silkworms deliver meaningful protein and hydration without piling on fat. They're the feeder you can offer liberally without worrying about weight gain.
Moisture: 83%
Silkworms are essentially edible water. At 83% moisture, they provide more hydration per gram than any common feeder except hornworms (~85%). That's especially valuable for:
- Chameleons, which are notoriously hard to keep hydrated in captivity.
- Reptiles in shed, where good hydration supports clean, complete sheds.
- Recovering or dehydrated animals, which benefit from moisture-rich feeders.
- Species that don't drink from standing water, including many arboreal reptiles that rely on food moisture.
Protein: 9% — read this carefully
Here's where keepers get misled. You'll see silkworms described as "60% protein." That figure is on a dry-matter basis — after you remove the water. On an as-fed basis, the basis that matters when your animal actually eats one, silkworm protein is about 9%, lower than roaches (~20%) or crickets (~15–21%). That's the trade-off for their ultra-low fat and high moisture: as-fed, they're mostly water.
On a dry-matter basis, silkworm protein is indeed high — roughly 53–64%, competitive with or exceeding most feeders. Both numbers are true; they just describe different things. The practical conclusion is the same either way: silkworms are not ideal as a sole staple for an animal with high daily protein needs (a growing juvenile, say). They shine as a regular supplement alongside a protein-dense staple like discoid roaches, where the combination delivers high protein from the roaches plus the low-fat, high-moisture benefits of silkworms.
Calcium-to-phosphorus ratio: 0.77:1
Silkworms have one of the better Ca:P ratios among common feeders — roughly on par with discoid and dubia roaches, and dramatically better than mealworms (~0.04:1) or crickets (~0.13:1). That said, 0.77:1 is still phosphorus-heavy, so you still dust with calcium. The honest framing: silkworms give you a better starting point than most feeders, not an excuse to skip supplementation. Nearly every feeder insect is phosphorus-heavy and needs calcium dusting; silkworms are simply less lopsided than the worst offenders.
Zero chitin
Unlike every other common feeder, silkworms have no hard exoskeleton. They're entirely soft-bodied throughout the larval stage — the stage you feed off. That means:
- Zero impaction risk from chitin buildup in the digestive tract.
- Effortless digestion, even for juveniles, sick animals, or species with sensitive guts.
- No accumulating chitin stress of the kind heavy cricket or mealworm feeding can cause.
For juvenile bearded dragons, young leopard geckos, and chameleons of every age, the absence of chitin makes silkworms one of the safest feeders you can offer.
Serrapeptase: the unique enzyme
Silkworms are the only common feeder that contains serrapeptase (serratiopeptidase), a proteolytic enzyme produced naturally in the silkworm gut. Serrapeptase has been studied in human and veterinary medicine for potential anti-inflammatory and immune-supporting properties. Controlled studies in reptiles are limited, so I'll be honest about the uncertainty: many experienced keepers and vets anecdotally report better digestive and immune health in reptiles fed silkworms regularly, but whether that's the serrapeptase specifically or just the silkworm's overall nutritional quality is genuinely debated. Either way, it's a dimension no other feeder offers.
How silkworms compare to other feeders
| Feeder | Protein | Fat | Moisture | Ca:P | Chitin |
|---|---|---|---|---|---|
| Silkworms | 9% | 1% | 83% | 0.77:1 | None |
| Discoid roaches | 20% | 7% | 65% | 0.77:1 | Moderate |
| Dubia roaches | 23% | 7% | 61% | 0.74:1 | Moderate |
| Hornworms | 9% | 3% | 85% | 3.07:1 | Minimal |
| BSFL | 17% | 14% | 61% | 6.92:1 | Moderate |
| Crickets | 15–21% | 6% | 73% | 0.13:1 | Moderate |
| Mealworms | 20% | 13% | 62% | 0.04:1 | High |
| Superworms | 20% | 18% | 58% | 0.16:1 | High |
| Waxworms | 14% | 25% | 58% | 0.13:1 | Low |
Two things jump out. First, BSFL is the rare feeder with calcium higher than phosphorus (Ca:P ~6.9:1) — the exception to the "every feeder needs calcium dusting" rule. Second, the fat column is a obesity map: silkworms at the safe end, waxworms and superworms at the "treat only" end.
Where silkworms fit in a feeding rotation
Silkworms aren't a sole staple — their as-fed protein is too low to carry a growing animal alone. They excel as a premium supplement that delivers benefits no other insect can. A complete rotation looks like this:
- Staple (daily): discoid roaches — high protein, moderate fat, excellent gut-loading.
- Premium supplement (2–3×/week): silkworms — ultra-low fat, hydration, serrapeptase, zero chitin.
- Calcium boost (1–2×/week): BSFL — naturally calcium-rich.
- Hydration treat (1–2×/week): hornworms — ~85% moisture, stimulates appetite.
This four-feeder program — roaches, silkworms, BSFL, hornworms — covers protein, low-fat nutrition, calcium, hydration, and variety, which is about as complete as an insect diet gets.
Which animals benefit most from silkworms
The data points to specific use cases where silkworms earn their cost:
- Obesity-prone species — bearded dragons, leopard geckos, blue tongue skinks. The 1% fat lets you offer protein and variety without weight gain.
- Chameleons — the low fat, high moisture, and zero chitin together make silkworms one of the best routine feeders for a notoriously finicky, easily dehydrated group.
- Juveniles and recovering animals — no chitin means effortless digestion and zero impaction risk, ideal for young geckos and dragons or any animal bouncing back from illness.
- Picky eaters — silkworms move with a gentle wriggle that triggers a strike response, and many reptiles take them eagerly even when refusing other feeders.
- Animals in shed or that don't drink standing water — the 83% moisture supports clean sheds and hydrates arboreal species that rely on food for water.
The flip side: a fast-growing juvenile that needs maximum daily protein shouldn't live on silkworms alone, and budget-conscious keepers feeding large collections will find them pricier per gram than roaches. Use them where their unique qualities matter, not as a blanket staple.
How to store and feed silkworms
Silkworms are delicate, so a little handling discipline keeps them feeding well:
- Keep them at room temperature (about 70–80°F) in their shipped container with their mulberry-based chow. Don't refrigerate them — unlike hornworms, cold harms silkworms.
- Keep the cup dry and ventilated. Condensation breeds mold, the most common cause of a silkworm die-off. Wipe moisture and remove any soft or discolored worms.
- Feed them warm and active — a wriggling silkworm triggers a far better feeding response than a cold, still one.
- Dust before feeding on your species' normal calcium schedule, since the Ca:P ratio, while decent, is still phosphorus-heavy.
A healthy silkworm is plump, pale cream, and moving; limp or darkened ones should be discarded.
One nutritional note on handling: unlike roaches or crickets, you can't meaningfully gut-load silkworms in the day before feeding, because they eat only their mulberry-based chow. Their nutritional value is essentially baked in by what they've been raised on, so the levers you control are freshness (feed them while plump and healthy) and calcium dusting at feeding time. That makes buying from a quality source that raises them well more important for silkworms than for feeders you can top up yourself.
The bottom line
Silkworms earn the "premium" label on hard data: the lowest fat of any feeder, zero chitin, exceptional moisture, a decent Ca:P ratio, and the unique presence of serrapeptase. They're not the cheapest feeder and not the highest in raw as-fed protein — but they deliver qualities no other insect replicates. For obesity-prone species, hard-to-hydrate animals, juveniles, and picky eaters, they're an investment in long-term health. When you want them on hand, All Angles Creatures stocks fresh silkworms with a live arrival guarantee.
Feeding leopard geckos specifically? See my complete guide to silkworms for leopard geckos, or browse the full exotic-animals care library. For an independent nutrition reference, the USDA FoodData Central database documents insect and feeder nutrient composition.