Discoid Roaches vs. Katydids for Blue Tongue Skinks
I keep blue tongue skinks, and the question I get most is some version of "what should I actually be feeding for protein?" These lizards are omnivores — in the wild they eat insects, snails, carrion, fruit, and vegetation — so the protein half of the diet has a lot of room for choice. Two feeders that come up are discoid roaches (Blaberus discoidalis) and katydids. I've used both. Here's the honest comparison, not the marketing version.
What a blue tongue skink actually needs
Blue tongues (genus Tiliqua) are robust, ground-dwelling omnivores that reach roughly 18–24 inches. A healthy captive diet runs about half animal protein and half plant matter (greens, vegetables, a little fruit), with the protein side being the part insects fill.
Feeding cadence: adults roughly 2–3 times a week, juveniles more often because they're growing fast. Whatever insect you choose has to be appropriately sized (nothing wider than the space between the eyes is the usual rule of thumb), digestible, and — critically — gut-loaded and dusted with calcium, because that's where the real nutritional value comes from.
The honest nutrition comparison
On paper, these two are closer than you'd expect. Both are decent-protein, moderate-fat insects.
| Discoid roach | Katydid | |
|---|---|---|
| Protein (dry matter) | ~20–24% | ~20–25% |
| Fat (dry matter) | ~6–8% | ~6–10% |
| Exoskeleton | Soft, easy to digest | Harder, more chitin |
| Calcium balance | Phosphorus-heavy — must dust | Phosphorus-heavy — must dust |
| Availability | Year-round, captive-bred | Seasonal, often wild-caught |
| Storage | Weeks in a warm bin | Poor; fragile, short-lived |
The big myth to clear up: neither of these has a naturally good calcium-to-phosphorus ratio. You'll see claims that discoids (or katydids) come pre-balanced — they don't. Like almost all feeder insects, both are phosphorus-heavy, and feeding them undusted over time is a fast track to metabolic bone disease in a skink. Gut-load for 24–48 hours and dust with calcium before feeding, every time. (The genuine high-calcium exception among feeders is black soldier fly larvae — but that's a different feeder.)
Where discoids pull ahead nutritionally
The difference that matters in practice is the exoskeleton. Discoid roaches are notably soft-bodied. Katydids carry a tougher, more chitinous shell, which is harder on the digestive tract — a real concern for juveniles or any skink prone to impaction. For a feeder you're using regularly, softer is safer.
Behavior, handling, and sourcing
This is where the gap really opens up.
Discoid roaches are calm, slow-moving, and nocturnal. They don't climb smooth surfaces and the adults won't fly off, so they stay put in a smooth-walled bin and are easy to collect at feeding time. They're captive-bred, sold year-round, and ship well — you can keep a colony or just reorder. They're cheap per insect and effectively maintenance-free.
Katydids are the opposite: fast, jumpy, strong-legged, and well camouflaged, which makes them a pain to catch and contain. They're mostly seasonal and frequently wild-caught, which brings two problems — pesticide exposure and parasite risk. They're fragile in shipping (higher transit mortality), they don't store, and they cost more when you can find captive-bred stock at all. Their one upside is enrichment: the movement triggers a skink's hunting drive, which is genuinely fun to watch.
Risks worth taking seriously
Discoid roaches:
- Oversized roaches can be a choking/impaction risk for small or juvenile skinks — size them correctly.
- Overfeeding any protein leads to an overweight skink; keep the plant half of the diet honest.
- Some keepers develop a mild handling allergy over time (true of many feeder insects).
Katydids:
- Wild-caught insects may carry pesticides or parasites — the biggest single reason I don't use them as a staple.
- The harder exoskeleton raises impaction risk, especially in young skinks.
- Strong mandibles mean a live one can nip; don't leave them loose in the enclosure with a slow-feeding skink.
My verdict
For a blue tongue skink, discoid roaches are the staple; katydids are an occasional treat at most. Discoids give you consistent nutrition, a soft body that's easy to digest, reliable captive-bred sourcing, and trivial husbandry. Katydids offer enrichment and variety but lose on safety (wild-caught risk, hard shell), consistency, and practicality. If you want to add them for novelty, source captive-bred insects and keep it rare.
What actually optimizes a skink's health isn't picking one perfect bug — it's variety on a reliable base. Build the protein half around dusted, gut-loaded discoid roaches, rotate in other safe feeders for diversity, and keep the greens and vegetables coming. If you're sourcing a steady supply, All Angles Creatures stocks captive-bred discoid roaches sized for skinks.
For balance, also keep in mind what the science orgs say about feeder nutrition and supplementation — the Merck Veterinary Manual's reptile nutrition overview is a solid, non-commercial reference on why dusting and gut-loading matter.
Comparing other feeders too? See Discoid Roaches vs. Termites for Blue Tongue Skinks and the full exotic animal care guides.