This guide covers size matching — how to choose insects at the right size for your dragon’s age and head width. For which insects to feed, see our best feeder insects roundup; for gut-loading, see how to gut-load; for impaction triage, see our impaction guide.
The eye-spacing rule
The single most useful sizing rule in bearded dragon husbandry:
Insects should be no wider than the space between your dragon’s eyes.
This applies to crickets, dubia roaches, and other hard-bodied insects. Worms and grubs (mealworms, superworms, BSFL, hornworms) can be slightly longer because their bodies are soft and flexible, but they should still be appropriately sized for the dragon’s jaw width [$TRAE_REF](https://reptifiles.com/bearded-dragon-care-packet/bearded-dragon-food/)[$TRAE_REF](https://www.drrosiedvm.com/learn/articles/bearded-dragon-not-eating).
The rule exists for two reasons:
- Hard-bodied insects that are too wide can lodge in the throat or upper digestive tract, causing choking or impaction [$TRAE_REF](https://hospital.cvm.ncsu.edu/services/small-animals/nutrition/caring-for-your-pet-bearded-dragon/).
- Oversized prey can suppress appetite (the dragon is full from one bug) and reduce overall dietary variety.
The RSPCA’s parallel rule — “no bigger than the dragon’s mouth” — is the same idea expressed differently [$TRAE_REF](https://www.rspca.org.uk/en/adviceandwelfare/pets/other/beardeddragon).
[IMAGE: eye-spacing measurement diagram, source-needed, alt=”Diagram showing eye-spacing measurement on bearded dragon with calipers comparing width to cricket length”]
Size chart by dragon age
Most keepers size insects by life stage rather than measuring the dragon’s head. The table below covers the commonly available sizes from US pet stores; specialty sizes may differ.
| Life stage | Age range | Cricket size | Dubia / discoid roach size | Mealworm / superworm | BSFL (CalciWorms) |
|---|---|---|---|---|---|
| Hatchling | 0–2 months | ⅛″ pinhead | ⅛″ nymph | Skip (chitin too thick) | ⅛–¼″ |
| Baby | 2–4 months | ¼″ small | ¼″ nymph | Skip or micro mealworms only | ¼″ |
| Juvenile | 4–8 months | ½″ medium | ⅜–½″ nymph | Standard mealworms OK | ¼–½″ |
| Sub-adult | 8–18 months | ¾″ large | ½–¾″ medium | Standard + occasional superworm | ½″ |
| Adult | 18 months+ | ¾–1″ adult | ¾–1″ adult | Standard mealworms; superworms ≤1.5″ | ½–¾″ |
Notes:
- “Skip” doesn’t mean “never.” Some keepers introduce micro mealworms (⅛″) to hatchlings; the main caution is that standard mealworms’ thicker chitin can be harder to digest for very small dragons.
- BSFL (CalciWorms, Phoenix Worms) are pre-loaded with calcium and are the only feeder routinely recommended at any size — they’re pre-sized by the producer and have the highest Ca:P ratio (55:1) of any common feeder.
- Superworms are not for juveniles under 6 months. Their thicker chitin and higher fat content make them harder to digest; reserve them as an adult treat (1–2 per week max) [$TRAE_REF](https://vcahospitals.com/know-your-pet/bearded-dragons-feeding).
[IMAGE: feeder insect size comparison, source-needed, alt=”Side-by-side size comparison of pinhead cricket 1/4 inch cricket 1/2 inch cricket and adult cricket next to bearded dragon head outline”]
Per-species sizing notes
Crickets
The most common feeder, but the most size-variable at the pet store. Pet-store “small” crickets range from ¼″ to ½″; “medium” from ½″ to ¾″. When in doubt, pick the smaller end of the range you’re offered. A slightly under-sized cricket is safer than a slightly over-sized one.
Dubia roaches
More size-consistent than crickets because they’re sold by life stage (nymph vs adult). Nymphs under ½″ work for juveniles; adults (¾″+) work for adults. Dubia chitin is softer than cricket chitin, which makes them marginally easier to digest at the upper size limit.
Mealworms
Standard mealworms are 1″ long but very thin (~⅛″ wide). The width matters more than the length — they fit most juvenile and adult dragons by width even when they’re long. Skip mealworms under ⅛″ wide for hatchlings [$TRAE_REF](https://vcahospitals.com/know-your-pet/bearded-dragons-feeding).
Superworms
Wider and longer than mealworms (1.25–1.5″ × ¼″). Their chitin is also thicker. Adults only, in rotation with softer insects. Avoid superworms as a daily staple.
Hornworms
Very high moisture, soft body, low chitin. 1–1.5″ hornworms are fine for juveniles and adults as a hydration boost. They’re expensive to feed daily but useful as a “wet food” rotation.
Black soldier fly larvae (BSFL / CalciWorms)
Pre-loaded with calcium; soft body; no chitin concerns. The producer sizes them, so buying “small” or “medium” maps directly to dragon age. This is the easiest feeder to size correctly.
What happens if an insect is too big
Three risks are documented, in increasing order of severity:
- Appetite suppression. A too-big meal fills the dragon up on a single prey item and discourages greens intake, slowing the transition to adult diet proportions.
- Choking / jaw stress. Oversized crickets or roaches can lodge in the mouth or stretch the jaw, especially in juveniles. The dragon may paw at its mouth or refuse additional food.
- Impaction. Hard chitin in oversized prey can accumulate in the digestive tract. Signs: not eating, not eating + not pooping for 5+ days, distended abdomen, hind-limb weakness. Impaction is a vet-visit event — see our impaction guide for triage [$TRAE_REF](https://www.drrosiedvm.com/learn/articles/bearded-dragon-not-eating)[$TRAE_REF](https://hospital.cvm.ncsu.edu/services/small-animals/nutrition/caring-for-your-pet-bearded-dragon/).
Two safety tips:
- Avoid loose substrate feeding. Sand or walnut-shell substrate + oversized prey is the textbook impaction setup. Use a feeding dish or feed in a separate enclosure [$TRAE_REF](https://corhs.org/uploaded/89bfcdf0397c3e18c1dff810553f6336_CoRHS_Bearded_Dragon_Care_GuideCURRENT.pdf).
- Never feed wild-caught insects. They can be both larger than expected and toxic (fireflies are lethal; many wild insects carry pesticides or parasites) [$TRAE_REF](https://vcahospitals.com/know-your-pet/bearded-dragons-feeding).
When to size up
Three signals mean it’s time to move up:
- The current size is being eaten in 2–3 bites instead of one. This means the prey is now too small to satisfy and is becoming a “snack” rather than a meal.
- The dragon is searching the enclosure for more within minutes of finishing. Appetite is up but prey doesn’t satisfy.
- Body condition is dropping. Underweight despite feeding at the current size means the dragon is processing more calories than it’s the is taking in.
Don’t size up based on age alone — measure against the dragon’s actual head width.
Common mistakes to avoid
1. Buying “large crickets” for a juvenile
Pet-store “large” crickets are often ¾–1″, well above the eye-spacing rule for of juveniles under 6 months. Default to medium or small until the dragon’s head visibly widens.
2. Feeding superworms as a daily staple
Superworms are 1.5″ long with thick chitin. They’re fine as 1–2 per week treat; they’re not a staple for any age [$TRAE_REF](https://vcahospitals.com/know-your-pet/bearded-dragons-feeding).
3. Mixing sizes in the same meal
If you offer both ½″ crickets and 1″ adult dubia in the same meal, the dragon may try the larger one first. Either size up entirely or stay at the current size entirely for 1–2 weeks.
4. Ignoring the dragon’s body condition
A well-fed juvenile looks plump at the base of the tail and across the back legs. If your juvenile looks thin despite eating at the recommended size, size up sooner rather than the the later.
5. Using substrate as a feeder delivery method
Tossing crickets onto loose substrate increases impaction risk. Use a dish or feed in a separate bin for hard-bodied insects.
Quick answers
How big should crickets be for a bearded dragon?
No wider than the space between the dragon’s eyes. For hatchlings, that’s pinhead (⅛″). For juveniles, ¼–½″. For adults, ¾–1″.
Can a baby bearded dragon eat mealworms?
Standard mealworms’ thicker chitin is harder to digest for very small dragons. Skip mealworms under ⅛″ wide for hatchlings; standard mealworms are fine from 4–6 months onward.
Can a bearded dragon choke on a cricket?
Yes — oversized hard-bodied insects can lodge in the throat. Use the eye-spacing rule and supervise feeding if you’re unsure.
What size dubia roach for an adult bearded dragon?
Adult dubia roaches (¾–1″) are appropriate for adult dragons over 18 months. Medium dubia (½″) work for juveniles.
Are superworms safe for bearded dragons?
Yes for adults over 6 months, in rotation (1–2 per week). Their thick chitin makes them unsuitable as a daily staple or for juveniles.
Do I need to measure my dragon’s eye spacing?
Not literally — most keepers use the life-stage size chart above as a proxy. If in doubt, error on the smaller side. An under-sized cricket is safer than an over-sized one.
Sources & review
- ReptiFiles – Bearded Dragon Food (eye-spacing rule): https://reptifiles.com/bearded-dragon-care-packet/bearded-dragon-food/
- Dr. Rosie DVM – Bearded Dragon Not Eating: https://www.drrosiedvm.com/learn/articles/bearded-dragon-not-eating
- VCA Animal Hospitals – Bearded Dragons Feeding: https://vcahospitals.com/know-your-pet/bearded-dragons-feeding
- NC State CVM – Caring for Your Pet Bearded Dragon: https://hospital.cvm.ncsu.edu/services/small-animals/nutrition/caring-for-your-pet-bearded-dragon/
- RSPCA – Caring for your bearded dragon: https://www.rspca.org.uk/en/adviceandwelfare/pets/other/beardeddragon
- Colorado Reptile Humane Society – Bearded Dragon Care Guide (PDF): https://corhs.org/uploaded/89bfcdf0397c3e18c1dff810553f6336_CoRHS_Bearded_Dragon_Care_GuideCURRENT.pdf
Last reviewed: 2026-09-01 · Next scheduled review: 2027-03-01 · Editor: Bearded Dragon Hub Editorial Team
Educational content only. Not a substitute for hands-on veterinary care. A dragon showing signs of impaction (not eating, not pooping for 5+ days, distended abdomen, hind-limb weakness) should see an ARAV-listed exotics veterinarian promptly.