Silkworms vs Hornworms: Which Feeder Is Better?

Silkworms and hornworms are the two soft-bodied "premium" feeders most reptile keepers reach for when crickets and roaches alone aren't enough. They look superficially similar — both are caterpillar-stage larvae, both are easy to digest, both are visually striking — but they play different roles in a reptile's diet. Silkworms are a bone-and-balance feeder. Hornworms are a hydration-and-treat feeder. Knowing which is which prevents the most common mistake people make with both.

Side-by-side nutrition

Metric	Silkworms (Bombyx mori)	Hornworms (Manduca sexta)
Protein (dry weight)	~64%	~9% (wet) / ~37% (dry)
Fat	~10%	~3% (wet)
Calcium : Phosphorus	~1 : 1.4	~1 : 3
Moisture	~76%	~85%
Mature size	~7 cm at peak	~10 cm at peak

The differences that matter for keepers: hornworms are nearly all water (excellent for hydration, less so for nutrient density), and silkworms have meaningfully better calcium balance.

When to choose silkworms

For ongoing nutritional value

Silkworms are higher in protein per gram and have a much better Ca:P ratio. They are the right call when you want a feeder that actually moves the needle on a reptile's nutrition rather than just filling them up.

For everyday rotation

You can feed silkworms every other day to most reptiles without concern. They're calorically modest, well-balanced, and don't risk over-supplementation.

For young animals building bone

The calcium ratio favors growth. For hatchling and juvenile reptiles, silkworms are the more useful staple supplement.

When to choose hornworms

For dehydration recovery

An 85% water content makes hornworms the single best feeder for a reptile coming back from a heat-related crash, post-shed dehydration, or constipation. A handful of hornworms can resolve mild dehydration faster than a soak.

For finicky eaters

Hornworms are bright blue-green and wiggle. They are visually compelling and trigger feeding response in animals that have refused other prey. They are the "treat to break a hunger strike" feeder.

For variety in adult diets

Once a week, hornworms add genuine novelty to an established adult's diet. The animal looks forward to them.

Why neither should be the staple

Both feeders share a problem: they are nutritionally one-note. Hornworms are mostly water; silkworms are mostly mid-range protein. A 100% silkworm diet leaves the gut underexercised (no chitin) and undercooked on calorie density. A 100% hornworm diet undernourishes outright.

Crickets and discoid roaches remain the staples in most well-built reptile rotations. Silkworms and hornworms are supplements. The mistake isn't choosing one over the other — it's making either of them the entire diet.

Sizing comparison

Hornworms grow much larger than silkworms — peak hornworm size (~10 cm) is roughly 1.5× peak silkworm size (~7 cm). For a small leopard gecko or hatchling bearded dragon, that means hornworms can be size-limiting in a way silkworms aren't. Order small hornworms (1–2 cm) for animals under 6 inches; silkworms scale down to under 1 cm for the very smallest hatchlings.

Storage practicalities

Silkworms need fresh mulberry chow every other day, kept at 72–82°F, never refrigerated. A batch keeps 2–4 weeks before pupating.

Hornworms arrive in a pre-loaded "horn habitat" with their food gel pre-portioned. Keep at room temperature and they last 2–3 weeks before pupating into moths. They grow rapidly — a small hornworm can become large in 7–10 days, so size them at delivery and feed off the appropriate stage promptly.

Cost

Hornworms tend to be slightly more expensive than silkworms per gram, but their volume-to-meal ratio means a single hornworm often replaces several silkworms in a meal. The economics are roughly comparable.

The recommended pairing

Most experienced keepers run both. A reasonable rotation pattern for a juvenile bearded dragon or large adult leopard gecko:

• Crickets or discoid roaches: 4–5 days per week (staple)
• Silkworms: 1–2 days per week (calcium and protein balance)
• Hornworms: 1× per week or after a fast (hydration and variety)
• Other: BSFL, superworms, or waxworms rotated in occasionally

Bottom line

Silkworms for nutritional balance, hornworms for hydration and refusal-breaking. Neither replaces a calorie-dense cricket-or-roach staple, and using both — not just one — is what separates a healthy long-term reptile diet from a nutritional gap. Browse the full feeder lineup or read more on diet rotation in our Creature Insights blog.