Feeding Blue-Tongue Skinks: Discoid Roaches vs. Phoenix Worms
- Role
- Staple feeder
- Protein
- ~20%
- Fat
- ~6.5%
- Moisture
- ~60%
- Chitin
- low
- Ca:P
- 1:3
- Calcium-rich
- No (dust it)
- Best for
- Most insectivores — beardies, geckos, frogs, monitors
I keep blue-tongue skinks, and the question I get most from new owners is whether to feed discoid roaches or Phoenix worms. The honest answer is "both, for different reasons." They're not really competitors — one is your protein staple and the other is your calcium insurance. Here's how they actually compare, and how I rotate them.
What blue-tongue skinks need from their food
Blue-tongues (genus Tiliqua, native to Australia, Indonesia, and New Guinea) are omnivores, not insectivores. A captive diet should roughly mirror the wild mix: a base of leafy greens and vegetables, some fruit, and a meaningful share of animal protein. Common staples include collard and mustard greens, squash, blueberries and mango in moderation, and protein from insects or lean meats.
Adults typically eat about 2–3 times per week; juveniles eat more often and lean more heavily on protein for growth. Within that protein share, the feeder you choose matters — not just for protein, but for the calcium-to-phosphorus balance that keeps a skink's skeleton healthy. Get that balance wrong and you risk metabolic bone disease (MBD); get it right and you've got a thriving, active lizard.
Why feeder choice matters more than people think
Three factors drive a good feeder pick for skinks:
- Calcium-to-phosphorus (Ca:P) ratio — the big one. The target for reptiles is roughly 2:1 to 1:1 calcium-to-phosphorus. Too much phosphorus blocks calcium absorption and drives MBD.
- Digestibility and size — softer-bodied, appropriately-sized prey is easier on juveniles and animals with sensitive guts; hard, chitin-heavy prey in excess risks impaction.
- Feeding response — skinks are deliberate, not frantic hunters, but a little prey movement still triggers interest and provides enrichment.
Discoid roaches and Phoenix worms land in very different spots on these axes, which is exactly why they pair so well.
Discoid roaches: the protein staple
Discoid roaches (Blaberus discoidalis) are tropical, non-climbing, non-flying, low-odor feeders that are easy to keep and breed. For skinks, their headline trait is protein density.
- Protein: high, around 20–22% as fed (gut-load dependent) — excellent for muscle and tissue maintenance.
- Fat: moderate, roughly 7–9% — energy without tipping a skink toward obesity.
- Moisture: about 60–70%, contributing to hydration.
- Behavior: slow-moving and grounded, so a substrate-foraging skink can catch them easily, and they won't climb out of an open feeding dish.
The catch — and it's important: discoids are phosphorus-heavy, with a Ca:P ratio of roughly 1:3 (more phosphorus than calcium). The old write-ups that call this "favorable" are wrong. You must dust discoid roaches with a quality calcium powder before feeding, and gut-load them well, or you risk MBD over time. Done right, dusted discoids are a superb skink staple.
Phoenix worms: the calcium specialist
Phoenix worms — also sold as calci-worms or BSFL — are the larvae of the black soldier fly (Hermetia illucens). Their claim to fame is the one thing discoids lack.
- Calcium: naturally very high, with a Ca:P ratio around 5:1 — they bring more than enough calcium to the table and generally need no dusting.
- Protein: decent, roughly 15–17% — lower than discoids, but highly digestible.
- Fat: low, about 4–6% — good for weight management.
- Digestibility: soft-bodied and small, easy on juveniles and animals prone to impaction.
- Convenience: raised in clean conditions, they typically arrive gut-loaded and mess-free, and their natural wriggling triggers a strong feeding response.
Phoenix worms are the rare feeder you don't have to dust for calcium, which makes them genuinely valuable for bone health and for juvenile skinks. Their limitation is size and protein — small and lower-protein, so they're a complement, not a standalone staple. You can source them from All Angles Creatures' black soldier fly larvae collection.
Head-to-head comparison
| Factor | Discoid Roach | Phoenix Worm (BSFL) |
|---|---|---|
| Protein | ~20–22% (higher) | ~15–17% (moderate) |
| Fat | ~7–9% (moderate) | ~4–6% (low) |
| Ca:P ratio | ~1:3 — must dust with calcium | ~5:1 — naturally calcium-rich |
| Size | Medium–large (1.5–2 in) | Small |
| Digestibility | Good for adults; chitin tougher on juveniles | Excellent, soft-bodied |
| Best for | Everyday protein staple | Calcium support, juveniles, weight control |
| Home breeding | Easy, self-sustaining colony | Possible but more temperature-sensitive |
| Needs gut-loading | Yes | Usually arrives gut-loaded |
Digestibility and ease of feeding
Discoids carry a chitinous exoskeleton that adult skinks handle without trouble — blue-tongues are built to crush and chew — but it can be a bit much for very young skinks or animals with sensitive digestion. Their slow movement makes them easy to catch and adds a little hunting enrichment.
Phoenix worms are the gentler option: small, soft, and quick to digest, which lowers impaction risk for juveniles and recovering animals. Their wriggle is enticing, and there's no gut-loading prep. For a hatchling or a fussy eater, they're often the easier sell.
Cost and availability
Discoids are moderately priced and most reliably bought from online specialty breeders; bulk orders bring the per-roach cost down, and a colony you breed at home eventually costs almost nothing to maintain. Phoenix worms are affordable per container but, because they're small and shorter-lived once mature, the recurring cost adds up if you lean on them heavily — and they're tougher to home-produce at scale because they're temperature-sensitive. For long-run cost, discoids win; for grab-and-go convenience, Phoenix worms do.
A regional note: discoid roaches are legal in many places where other feeder roaches are restricted, but check your local rules. Phoenix worms face essentially no such restrictions.
How I actually feed them: use both
The right move for a blue-tongue skink isn't to pick a winner — it's to rotate. I use dusted discoid roaches as the everyday protein staple and Phoenix worms as regular calcium-rich support, especially for growing juveniles. Together they cover the bases: discoids bring the protein, Phoenix worms bring the calcium, and rotating them (alongside greens, vegetables, and the occasional fruit or lean protein) keeps the diet varied, balanced, and interesting enough that the skink stays keen at mealtime.
A simple working rule: build the protein share mostly on calcium-dusted discoids, work Phoenix worms in regularly for bone health, and never rely on any single feeder as the whole diet.
Safety basics
A few risks worth managing regardless of feeder: buy from reputable sources to avoid parasites and pesticide-exposed insects; don't overdo chitin-heavy prey with juveniles (impaction risk); always provide a varied diet to avoid nutrient gaps; and practice basic hygiene, since roach frass and shed parts can trigger allergies in sensitive people. When in doubt about supplementation or a sick animal, lean on a vet and a solid reference like the Merck Veterinary Manual's reptile section; university extension programs also publish good background on black soldier fly larvae and feeder nutrition.
Want the deeper feeder breakdown? See discoid roaches vs. other feeders and the full discoid roach biology guide.