Which is better for a blue tongue skink, discoid roaches or BSFL?

Neither wins outright. Discoid roaches are the better protein staple for adults; black soldier fly larvae are the better calcium source and the easier feeder for juveniles. Most keepers, myself included, use both in rotation rather than choosing one.

Do I need to dust discoid roaches with calcium?

Yes. Discoid roaches are phosphorus-heavy and need a light calcium dusting before feeding. Black soldier fly larvae are the exception, they carry usable calcium naturally and rarely need dusting.

Can blue tongue skinks eat BSFL whole?

Yes. BSFL are small (about 3/4 inch) and soft, so adult and juvenile skinks eat them whole with no sizing concerns. Just don't make them the only feeder, their small size means lots of them to satisfy an adult.

How much of a skink's diet should be insects?

Roughly 40 to 50% animal protein for most blue tongue skinks, balanced against 40 to 50% vegetables and about 10% fruit. Discoids and BSFL both count toward the protein half.

Will discoid roaches escape or infest my house?

No. Discoid roaches can't climb smooth walls or fly, and they can't survive in a typical home without tropical heat and humidity. An escapee is a dead end, not an infestation.

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Feeder Insects

Discoid Roaches vs. Black Soldier Fly Larvae for Blue Tongue Skinks

By Matt Goren · Updated June 26, 2026

I keep blue tongue skinks and I keep both of these feeders, so this is a comparison I make every week at feeding time. The short version: discoid roaches and black soldier fly larvae solve different problems, and the best diet uses both. Here's how they actually stack up.

What a blue tongue skink needs

Blue tongues (Tiliqua species) are ground-dwelling omnivores from Australia, Indonesia, and New Guinea. A balanced captive diet runs roughly 40 to 50% animal protein, 40 to 50% vegetables (collard, mustard, dandelion greens, squash, carrot), and about 10% fruit as a treat. Calcium and vitamin D3 are critical, skip them and you risk metabolic bone disease (MBD), the single most common husbandry failure in captive reptiles.

Both feeders here go on the protein side of that plate. The question is which one, when.

Discoid roaches at a glance

Discoid roaches (Blaberus discoidalis) are non-climbing, non-flying tropical roaches, 1.5 to 2 inches at adult size, slow, docile, and odorless. They can't scale smooth walls or fly, so they're easy to contain and there's no infestation risk in a normal home.

Protein: ~20 to 23% (dry matter), a strong lean protein staple.
Fat: ~5 to 8%, moderate, energy without obesity.
Moisture: ~65 to 70%, decent hydration.
Calcium:phosphorus: phosphorus-heavy, needs calcium dusting.
Chitin: relatively low, easier to digest than crickets or superworms.

Black soldier fly larvae at a glance

Black soldier fly larvae (Hermetia illucens), sold as Calci-Worms or Phoenix Worms, are small (up to ~3/4 inch), soft, cream-colored grubs harvested before they pupate into harmless non-biting flies.

Protein: good, but lower than discoids.
Fat: moderate, healthy fats including lauric acid.
Calcium:phosphorus: naturally calcium-rich, the rare feeder that usually needs no dusting.
Size/texture: small and soft, ideal for juveniles and picky eaters.
Convenience: ship in a sealed cup, no colony to keep, grab-and-go.

Head to head

Factor	Discoid roaches	Black soldier fly larvae
Protein	Higher	Moderate
Calcium	Needs dusting	Naturally high, the exception
Size	Large, meaty	Small, soft
Best for	Adult skinks, staple protein	Juveniles, picky eaters, calcium
Movement / feeding response	Slow, less stimulating	Wiggly, triggers hunting
Keeping	Live colony, hardy, long-lived	Sealed cup, short shelf life
Cost	Cheaper long term	Pricier per gram

How I actually use them

For an adult skink, discoid roaches are my protein workhorse, more meat per feeder, lean, and cheap to keep a colony going. I dust them with plain calcium before offering, because that phosphorus-heavy ratio is the one thing that'll bite you over time.

For a juvenile, a picky eater, or any week the diet's been light on calcium, BSFL come out. They're small enough to eat whole, soft enough for young jaws, and their built-in calcium covers a gap that dusting sometimes misses. Their wiggle also fires up a sluggish feeder's hunting drive.

In practice I rotate: discoids as the regular staple, BSFL worked in for calcium and variety. Variety itself matters, no single feeder is nutritionally complete, and rotation is what keeps a skink thriving.

Safety notes for both

Size to the skink: prey no longer than the gap between the eyes. Oversized roaches choke or impact.
Don't overdo BSFL: their high calcium is great in moderation but excess can push toward hypercalcemia.
Source clean stock: poorly kept roaches can carry Salmonella; buy from a breeder with a clean colony and live-arrival guarantee.
Gut-load before feeding: both feeders are only as good as what they last ate.

Where to buy and learn more

I keep my roach colony as the backbone of the protein rotation, AAC's discoid roach collection is where I restock. For the science on calcium-to-phosphorus balance and preventing MBD in reptiles, the Merck Veterinary Manual on metabolic bone disease in reptiles is the reference I trust.

Want to make your roaches last and breed? See my discoid roach care guide and the full exotic animals hub.

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