Silkworms
5 Surprising Benefits of Silkworms You Didn’t Know About
Silkworms (Bombyx mori) get talked about almost exclusively in two contexts: silk production and reptile feeding. Both are important, but they undersell what is actually a remarkably useful organism. The species has been domesticated for over 5,000 years, eats only mulberry leaves, and produces a feeder insect with one of the most favorable nutritional profiles in commercial breeding. Below are five things about silkworms that even experienced reptile keepers often do not know.
1. They are the only feeder with a near-balanced calcium-to-phosphorus ratio
Most feeder insects sit between 1:8 and 1:20 on the calcium-to-phosphorus ratio scale, which is why calcium dusting exists — keepers have to make up the gap to get closer to the 2:1 ratio that growing reptiles need. Silkworms come in around 1:1.4, which is within striking distance of the target without supplementation.
For comparison:
- Crickets: ~1:9
- Mealworms: ~1:14
- Superworms: ~1:18
- Dubia roaches: ~1:3
- Silkworms: ~1:1.4
- BSFL: ~3:1 (the only commonly bred feeder with calcium-positive Ca:P)
Silkworms and black soldier fly larvae are the two best naturally calcium-rich feeders available — silkworms for soft-bodied digestion, BSFL for calcium-surplus.
2. They are extraordinarily low in fat
At roughly 10% fat by dry weight, silkworms are dramatically leaner than most alternatives. Mealworms run 25–28% fat. Waxworms hit 50%+. Superworms sit around 17%. For keepers managing weight in adult bearded dragons, leopard geckos, or chameleons — species that gain weight easily on rich diets — silkworms let you offer satisfying meal volume without the fat load.
This is also why silkworms are a useful "rehabilitation" feeder. A reptile recovering from illness, surgery, or shipping stress often needs gentle, high-quality protein without metabolic strain. Silkworms deliver exactly that.
3. They are a complete protein
Most plant proteins are missing one or more essential amino acids — that's why human nutritionists talk about combining beans and rice. Insect proteins generally clear that bar, but silkworms specifically have been studied for their amino acid profile and shown to provide all nine essential amino acids in ratios that are well-suited to vertebrate metabolism. Studies in aquaculture have demonstrated that silkworm pupae meal can replace 30–50% of fishmeal in tilapia and trout diets without growth penalty.
For reptile keepers, this means a silkworm meal is a "full" meal in protein terms — you do not need to combine it with another feeder to round out the amino acid profile.
4. They contain a natural antimicrobial peptide
Silkworms produce a class of antimicrobial peptides called cecropins as part of their innate immune system. Cecropins were first isolated from silkmoths in the 1980s and have been studied extensively for use against antibiotic-resistant bacteria. While the levels in a feeder-stage silkworm are not therapeutic-dose for the reptile eating them, the underlying chemistry contributes to why silkworms are unusually disease-resistant in storage and rarely transmit pathogens to the animals consuming them.
This is part of why silkworms have such a strong "easy on the gut" reputation among keepers. They are not just easy to digest — they actively avoid carrying the kinds of microbial loads that can make a reptile sick.
5. They are domesticated to the point of dependency
This one is more biological curiosity than husbandry tip, but it explains why silkworms are reliable: Bombyx mori cannot survive in the wild. Five millennia of selective breeding have left the moths flightless, blind to predators, and entirely dependent on human husbandry. They cannot find mulberry leaves on their own, cannot escape predators, and cannot reproduce without human intervention to pair males and females.
For keepers, this means silkworms are uniquely uniform — every commercial silkworm shares essentially the same genetic background, eats the same diet (mulberry chow), and grows on a predictable 28-day timetable. There are no "wild-caught silkworms" because the species cannot live wild. That genetic and dietary uniformity translates into nutritional consistency that wild-caught feeders cannot match.
The practical takeaway
Silkworms are not just another option in the feeder lineup — they sit in a category of their own as the highest natural Ca:P-ratio common feeder, with the lowest fat content, a complete amino acid profile, and a domestication history that delivers unusual consistency. They are particularly valuable for:
- Hatchling and juvenile reptiles building bone
- Adults that need lean protein without weight gain
- Recovery feeding after illness or shipping stress
- Calcium-supplementation reduction (you still need some, just less)
The trade-off is cost and storage — silkworms are more expensive per gram than crickets or roaches, and they need clean mulberry chow refreshed regularly. For most keepers, that puts silkworms in the supplement column rather than the staple column. But once you understand what they bring nutritionally, it becomes obvious why experienced keepers always have a batch on hand. To explore using them in your rotation, see our care guides for species-specific feeding charts and rotation patterns.
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