Discoid Roaches vs. Silkworms for Geckos: A Keeper's Complete Feeder Guide
I keep feeder colonies running year-round, and the question I get more than almost any other from gecko keepers is some version of "which is better — roaches or silkworms?" Usually it's framed as a showdown, like one feeder is supposed to knock the other out and become the only thing in the cup. That framing is where people go wrong. After years of feeding both to a mixed collection, my honest answer is that this isn't a fight with a winner. It's a job board with two very different workers showing up: one is the dependable, low-cost staple you build a diet around, and the other is the premium specialist you bring in for picky eaters, hydration, and recovery.
This guide is the long version of that answer. I'll walk through what geckos actually need from a feeder, give you a full, honest nutritional profile of each insect (including correcting a few things the internet repeats that simply aren't true), put them side by side in a comparison table, get the calcium math right, and then get practical: palatability, digestibility, feeding schedules and portions by age, how to keep and store each one, gut-loading, the myths worth unlearning, and a clear verdict you can actually act on. Read it once end to end and you'll know exactly how to slot both feeders into a gecko's diet.
What geckos actually need from a feeder
Before you can compare two feeders, you have to know what you're optimizing for. Insectivorous and omnivorous geckos — leopard geckos, cresteds, gargoyles, tokays, day geckos, and the rest — don't get their nutrition from the bug itself so much as from what the bug is made of and what it last ate. A feeder insect is really a delivery vehicle. Five things determine how good a vehicle it is.
Protein builds and repairs tissue and drives growth. Juveniles and gravid (egg-carrying) females need it most. Most healthy adult geckos need adequate but not enormous amounts — a constant flood of the richest possible feeder isn't a goal, it's a path to an overweight animal.
Fat is energy. A little is essential; a lot is a problem. The single most common diet mistake I see in pet geckos isn't deficiency — it's obesity from fatty feeders given too often. Fat content is one of the biggest reasons to choose one feeder over another for everyday use.
Moisture matters more than most beginners realize. Hydration through food helps with digestion, healthy sheds, and recovery from illness. Geckos that won't drink from a dish often get most of their water from prey. A high-moisture feeder is a tool for hydration; a dry one isn't.
The calcium-to-phosphorus ratio (Ca:P) is the one that quietly causes disease. Geckos need roughly twice as much calcium as phosphorus in the overall diet (about a 2:1 ratio) to build and maintain bone. Get this chronically wrong and you get metabolic bone disease (MBD) — soft jaws, bent limbs, tremors, and eventually a crippled or dead animal. Here's the hard truth that the rest of this guide hangs on: almost every feeder insect is the opposite of what you want — phosphorus-heavy, with far too little calcium. That's not a defect in roaches or silkworms specifically; it's true of crickets, mealworms, superworms, hornworms, and nearly the whole feeder aisle. The fix is supplementation (dusting) and gut-loading, which I'll cover in detail. The Merck Veterinary Manual's overview of reptile nutrition is a solid, non-commercial reference if you want to go deeper on why this ratio is the thing that makes or breaks long-term skeletal health.
Digestibility and palatability are the practical tiebreakers. A feeder with a perfect profile is worthless if your gecko won't eat it, or if its hard shell causes impaction in a small or young animal. Texture, chitin (the hard material in insect exoskeletons), and how enticingly the bug moves all decide whether the meal actually lands.
Keep those five levers in mind — protein, fat, moisture, Ca:P, and digestibility/palatability — and the discoid-vs-silkworm comparison stops being about which is "best" and becomes about which lever each one pulls.
Discoid roaches: the full profile
Discoid roaches (Blaberus discoidalis) are a tropical roach from Central and South America, and they're the feeder I steer most keepers toward as a staple. (You'll occasionally see them mislabeled as Blaptica dubia — that's a different species, the dubia roach. Discoids are Blaberus discoidalis, and the distinction matters, especially because the two are regulated differently.) Adults reach about two inches, with a flat, glossy, tan-to-brown oval body. They're nocturnal, slow-moving, and docile, which makes them easy and unintimidating to handle even if you're squeamish about roaches.
Nutrition: a high-protein, moderate-fat staple
On an as-fed basis (the bug as your gecko actually eats it, water and all), discoids run roughly:
- Protein: ~20% — high, and well-balanced in amino acids. Solid for growth and maintenance.
- Fat: ~6–7% — moderate. Low enough to be an everyday feeder without driving obesity, which is exactly what you want in a staple.
- Moisture: ~60% — typical for a roach. Some hydration, but they're not a "water bug."
- Chitin: low. Compared with crickets and mealworms, discoids have a softer, lower-chitin shell, so they digest more easily than their size suggests.
That combination — good protein, controlled fat, easy digestion — is the textbook definition of a staple feeder. You can feed discoids as the backbone of the diet for years and not run into the fat problems superworms or waxworms cause.
The calcium truth about discoids
Here's where I have to directly contradict a lot of published care content, including the article this guide is built from. You will read that discoid roaches have a "balanced" or "moderately favorable" or even "2:1" calcium-to-phosphorus ratio, or that they offer "substantial calcium." That is wrong. Discoids, like nearly every feeder insect, are phosphorus-heavy with a poor Ca:P ratio. Their phosphorus content meaningfully outweighs their calcium.
What that means in practice is simple and non-negotiable: you must dust discoids with a calcium supplement. Gut-loading with calcium-rich greens helps nudge the numbers, but it does not turn a phosphorus-heavy bug into a calcium-rich one. Believing the "balanced ratio" myth and skipping the dust is a direct route to MBD. I treat the calcium shaker as part of every single roach feeding — plain calcium most of the time, calcium-with-D3 or a multivitamin on a rotation appropriate to the species and its lighting.
Behavior and containment
Two practical traits make discoids beginner-friendly. First, adults can't climb smooth vertical surfaces — glass, smooth plastic — so they won't scale a tank wall or a feeding cup. (They can grip rough surfaces like cardboard or screen, and tiny nymphs can slip through coarse mesh, which matters for colony bins but rarely for feeding off. You'll see sources call them "adept climbers"; that's another myth — adults simply don't climb smooth walls.) Second, they don't fly. Between not climbing glass and not flying, a roach that runs loose in the tank just hides until the gecko finds it later, rather than escaping into your house.
The standout advantage: you breed them yourself
The real reason discoids are the staple is economic and logistical. They're live-bearers — females carry the egg case internally and give birth to live nymphs — so a warm bin essentially restocks itself with no incubation, no fragile egg cases, and no special intervention. Set up a colony correctly and you stop buying feeders. For the complete colony build — enclosure, heat, humidity, breeding, and troubleshooting — see my dedicated guide on how to keep discoid roaches alive. The short version: warm (mid-80s to 90°F), humid, dark, fed protein plus produce, and patient for the first few months while the colony builds.
Silkworms: the full profile
Silkworms (Bombyx mori) are the larval stage of the domesticated silk moth, and they are a genuinely different kind of feeder. Where a roach is a tough little protein brick, a silkworm is a soft, plump, slow-moving caterpillar — and that physical difference is the whole point. They're entirely domesticated; they don't exist in the wild and depend completely on human care, which is part of why they're a premium feeder rather than a self-sustaining one.
Nutrition: soft, lean, and hydrating
Silkworm numbers get garbled online because people mix up "dry weight" and "as-fed." You'll see claims like "60–65% protein," which is a dry-matter figure — i.e., after you remove all the water. That's technically true and badly misleading, because silkworms are mostly water. On the as-fed basis that actually matters at feeding time, a silkworm is roughly:
- Moisture: very high, ~80%+ — this is their headline trait. They're one of the more hydrating feeders short of hornworms.
- Protein: moderate-to-good — meaningful protein, especially helpful for growth and recovery, but because so much of the worm is water, the per-worm protein is lower than the dry-weight number suggests.
- Fat: low — leaner than roaches, and far leaner than superworms or waxworms. Good for animals prone to weight gain.
- Chitin: very low / soft-bodied — there's no hard exoskeleton to speak of, so they're extremely easy to digest.
Silkworms also naturally contain serrapeptase, an enzyme produced in the silkworm, which is part of why keepers describe them as a gentle, easy-on-the-gut feeder. They're a clean, lean, soft, watery package — the opposite engineering choice from a roach.
The calcium truth about silkworms
Silkworms get the same myth treatment as discoids, just in the other direction: you'll read that they have an "excellent" or "near 2:1" Ca:P ratio that "negates the need for supplementation." That's overstated. Silkworms do have a better calcium balance than most feeder insects — that part is real and is a genuine point in their favor — and their high moisture and low fat help, too. But "better than most feeders" is a low bar, and they are not so calcium-rich that you should skip dusting. Dust silkworms with calcium just like you dust roaches. Treat their improved ratio as a nice bonus on top of supplementation, not a replacement for it. (If you want a feeder that genuinely runs a favorable Ca:P ratio with no help, that's black soldier fly larvae — not silkworms.)
Where silkworms shine: picky, young, and recovering geckos
The reason to keep silkworms in the rotation is everything their softness and water content unlock:
- Picky eaters. Silkworms wriggle constantly, and that movement plus their soft, easy texture triggers a feeding response in geckos that turn their noses up at a still, hard roach. They're my go-to for tempting a fussy animal.
- Hatchlings and small geckos. No hard shell means far lower impaction risk and easy digestion for tiny digestive systems.
- Recovery and hydration. For a gecko that's been sick, is dehydrated, or is struggling through a bad shed, the high moisture and gentle digestibility make silkworms one of the best "get something good into them" feeders available.
When I need a soft, hydrating feeder for a finicky or recovering gecko, I order live silkworms rather than trying to keep a colony going — All Angles Creatures stocks live silkworms raised on mulberry-based chow and sized for everything from hatchlings to adults. They arrive perishable and ready to feed, which fits how silkworms are actually used: a fresh batch when you need one, not a permanent fixture in the animal room.
The catch: perishable, pricier, and hard to sustain
Silkworms cost more per feeder than roaches, and they don't keep. They're raised on mulberry leaves or prepared mulberry chow, they're perishable, and — importantly — you must never refrigerate live silkworms; cold kills them. Breeding them at home is genuinely difficult: it requires fresh food, scrupulously clean conditions to avoid bacterial die-offs, and hand-pairing the moths to get eggs. For the vast majority of keepers, silkworms are a bought feeder, used in batches, not a colony you run.
Head-to-head comparison table
Here's the whole comparison at a glance. Treat the nutrition figures as approximate, as-fed values — they shift with diet, life stage, and source — but the relationships are reliable and they're what should drive your choices.
| Factor | Discoid roach (Blaberus discoidalis) | Silkworm (Bombyx mori) |
|---|---|---|
| Role | Everyday staple | Premium variety / treat |
| Protein (as-fed) | High (~20%) | Moderate–good (lower per-worm due to water) |
| Fat | Moderate (~6–7%) | Low |
| Moisture | ~60% | Very high (~80%+) |
| Chitin / digestibility | Low chitin, easy to digest | Soft-bodied, very easy to digest |
| Ca:P ratio | Poor (phosphorus-heavy) — must dust | Better than most feeders, but still dust |
| Hydration value | Modest | Excellent |
| Palatability | Slow, shy — some geckos ignore them | Constant wriggle — highly enticing |
| Best for | Daily diet, growth, all sizes | Picky eaters, hatchlings, recovery, hydration |
| Containment | Doesn't climb smooth walls, doesn't fly | Slow caterpillar, no escape risk |
| Keeping at home | Self-breeding colony — set and forget | Perishable; don't refrigerate; hard to breed |
| Cost | Cheap, especially if you breed them | Premium / pricier per feeder |
| Shelf life | Lives for months in a colony | Use within ~1–2 weeks of arrival |
The pattern jumps out: discoids win on cost, durability, sustainability, and everyday protein; silkworms win on hydration, digestibility, palatability, and suitability for vulnerable animals. They're not competing for the same slot.
Getting the calcium and supplementation right
This is the section that prevents disease, so I'm going to be blunt and specific. Both feeders are phosphorus-heavy relative to what a gecko needs (silkworms less so than discoids, but still). The whole job of supplementation is to flip the overall dietary calcium-to-phosphorus ratio toward the roughly 2:1 a gecko's bones need.
Dusting is the primary tool. Put a pinch of supplement powder and your feeders in a cup or bag, swirl gently to coat them, and feed promptly before it falls off. Use:
- Plain calcium (no D3) for most feedings. This is your default.
- Calcium with D3 on a schedule — D3 lets the body use calcium, but it's fat-soluble and can be overdosed, so it's periodic, not every meal. Geckos with strong UVB lighting need less dietary D3 than those kept without it; match your schedule to your lighting.
- A multivitamin lightly, on a rotation (often weekly), to cover vitamin A and the rest.
A common starting rhythm for many geckos is plain calcium at most feedings, D3-calcium once or twice a week, and a multivitamin once a week — but adjust to your species, age, and whether you provide UVB. When in doubt, the Merck Veterinary Manual and your reptile vet are better guides than any single internet schedule.
Gut-loading is the supporting tool. What a feeder ate in the 24–48 hours before you offer it becomes part of what your gecko eats. Feeding your roaches calcium-rich greens (collard, dandelion, mustard greens), squash, and a quality dry chow raises the nutrition your gecko receives. But — and this is the part people get backwards — gut-loading supplements dusting; it does not replace it. You cannot gut-load a phosphorus-heavy insect into a calcium-rich one. Do both.
The takeaway: dust every feeding of both insects, gut-load both, and don't let silkworms' slightly better ratio talk you out of the calcium shaker.
Palatability: winning over a picky gecko
Geckos are visual, movement-driven hunters. This is the axis where silkworms quietly dominate and where many "my gecko won't eat" problems get solved.
Discoid roaches are slow, shy, and nocturnal. A discoid dropped into a bright tank often freezes, tucks against a wall, or wedges under decor and goes still — and a still bug is, to a gecko, an invisible bug. That's the single biggest reason a perfectly nutritious roach gets ignored. Silkworms, by contrast, wriggle and squirm more or less continuously, and that motion is exactly the trigger a gecko's hunting brain is wired for. Add their soft, pleasant-to-eat texture and many geckos that snub roaches will take silkworms eagerly.
Practical tactics that work:
- Tong-feed. Offering a feeder with soft feeding tongs adds movement and puts the prey right in the gecko's line of sight. This rescues both reluctant roach-eaters and slow silkworms.
- Feed at dusk. Most geckos are crepuscular or nocturnal; offering food as the lights dim matches their natural hunting window and wakes up their appetite.
- Use silkworms as the gateway. For a gecko on a feeding strike or a new animal that's stressed, a wriggling silkworm is often the thing that gets it eating again — then you can reintroduce the staple.
- Keep roaches active. Warm, well-gut-loaded roaches move more than cold, hungry ones. A roach that's actually walking around is far more likely to get eaten.
The lesson: if palatability is your problem, silkworms are frequently the answer, and presentation (tongs, timing) fixes most of the rest.
Digestibility and hydration
For young, small, or compromised animals, how easily a feeder goes down matters as much as what's in it. Both of these feeders are on the gentle end of the spectrum — but silkworms are gentler.
Discoids have low chitin for their size, so they digest more easily than crickets or mealworms and are safe as a staple across most adult and well-grown juvenile geckos. For very small hatchlings, you still size carefully (more on that below) and lean on smaller nymphs.
Silkworms have essentially no hard shell at all. They're about as easy to digest as a feeder gets, which is precisely why they're a first choice for hatchlings, geckos with sensitive guts, and animals recovering from illness or impaction risk. Pair that with their very high moisture and silkworms become a genuine therapeutic tool: when a gecko is dehydrated, going through a difficult shed, or just off its food, a few soft, watery silkworms deliver hydration and nutrition in the gentlest possible form. Discoids, at ~60% moisture, simply can't do that hydration job as well.
This is the cleanest way to remember the split: discoids carry the protein, silkworms carry the water and the easy digestion.
Feeding schedule and portions by age
Numbers people can actually use. These are general gecko guidelines (leopard geckos are the reference point here, since they're the most common insectivorous gecko); always size and adjust to your specific species and animal.
Sizing the feeder
The universal rule: a feeder should be no larger than the width of the space between the gecko's eyes. Too big risks choking or impaction, especially in juveniles. For discoids that means small-to-medium nymphs for most geckos, larger nymphs and adults only for big species like tokays. For silkworms, match the worm's length and girth to the gecko — small silkworms for hatchlings, larger ones for adults.
Hatchlings and juveniles (growing)
Growing geckos are protein machines and should be fed daily or close to it. Offer appropriately sized feeders and let the gecko eat what it wants in a roughly 10–15 minute window (commonly a handful of small feeders per session, but appetite varies). This is where a discoid staple shines — daily protein at a sustainable cost — and where silkworms earn their keep for the smallest, most impaction-prone hatchlings and for tempting a juvenile that's being picky. Dust with calcium at essentially every feeding while they're growing; growth is when MBD does its worst damage.
Adults (maintenance)
Adult insectivorous geckos shift to every 2–3 days. Offer a few appropriately sized feeders per session. The goal flips from maximum growth to maintaining healthy body condition — you're now actively avoiding overfeeding. Keep discoids as the staple, rotate silkworms in as variety and for hydration, and use this stage to watch weight: a gecko with a fat tail is well-fed; a gecko getting too round needs fewer feedings or leaner choices.
A sample rotation
A simple, effective weekly pattern for an adult gecko might be: discoid roaches as the everyday staple two to three feeding days a week, silkworms as one of those feedings (for hydration and variety), all dusted appropriately, with the occasional hornworm for extra hydration or a superworm as a rare treat. The exact mix matters less than the principle: a roach staple plus rotated soft/hydrating variety beats any single feeder.
Keeping and storing each feeder
How you store these two could not be more different, and getting it wrong wastes money and animals.
Discoid roaches
For a feeding stash or a full breeding colony, discoids want warm, humid, dark. An opaque plastic bin with cross-ventilation (fine metal mesh over the openings), vertical cardboard egg flats for surface area and hiding, side-mounted heat on a thermostat at roughly 85–90°F for breeding, and 60–70% humidity is the whole setup. Feed them a dry protein chow plus rotated produce, keep water crystals (never an open dish nymphs can drown in) for hydration, and don't over-clean. A colony like this restocks itself for years. The full build — including how to fix a colony that's stopped producing — is in the discoid roach keeping guide.
Silkworms
Silkworms are the opposite: a short-term, perishable feeder you manage for days to a couple of weeks, not a colony you sustain. Rules that keep them alive:
- Room temperature, never the fridge. Cold kills silkworms. This is the number-one mistake — people store them like leftovers and find a cup of dead worms.
- Keep them dry and ventilated. Excess moisture and condensation breed the bacterial infections (silkworms are notoriously prone to die-offs) that wipe out a cup overnight. Crack the lid for airflow.
- Feed mulberry or prepared chow. They eat only mulberry leaves or commercial mulberry-based silkworm chow. Most arrive with chow in the cup; keep it fresh and don't let it mold.
- Cull immediately. Remove any dead, shriveled, or discolored worm the moment you see it — one sick worm can take the cup with it.
- Order what you'll use. Because they're perishable and don't breed easily at home, buy a batch sized to roughly one to two weeks of feeding rather than stockpiling.
The mental model: a discoid colony is an appliance you install once; silkworms are fresh groceries you buy as needed.
Gut-loading both feeders
Gut-loading is the cheapest upgrade to either feeder, and it applies to both. The principle: for 24–48 hours before you feed off, give the feeders rich, clean food so they're nutrient-packed at the moment your gecko eats them.
For discoids, gut-load with a quality dry chow plus calcium-rich greens (collard, dandelion, mustard), squash, sweet potato, and a little fruit for moisture. Pull anything before it rots, and skip salty, oily, or pesticide-treated produce.
For silkworms, the gut-load is essentially their normal food — fresh mulberry leaves or quality mulberry chow keep them at peak nutrition; just make sure it's fresh and clean in the day or two before feeding.
For both, two non-negotiables: buy/raise from a clean source (pesticide residue on produce or mulberry passes straight through the feeder into your gecko), and remember gut-loading is a complement to dusting, not a substitute. A well-gut-loaded, calcium-dusted feeder is the gold standard.
Cost and availability: the practical economics
For most keepers the deciding factor isn't a nutrition decimal point — it's money and convenience over the long run. The two feeders sit at opposite ends here, which is another reason they pair so well rather than compete.
Discoids are cheap, and they get cheaper. Per feeder, they're inexpensive to buy, and the moment you keep a breeding colony the marginal cost of each roach approaches zero — you're feeding the colony scraps of produce and a bit of chow, not buying bugs. For anyone with more than one insectivore, or a single hungry growing gecko, a discoid colony pays for itself fast and then keeps paying. Availability is excellent and stable: they're widely sold online and increasingly in shops, they ship well because they're hardy, and they're available year-round. The one regional wrinkle is regulation — discoids (Blaberus discoidalis) are the keepable feeder roach in places like Florida where dubia are restricted, so the species label genuinely matters when you order.
Silkworms are a premium feeder, and they stay premium. They cost more per worm up front, and because they're perishable and hard to breed at home, that cost recurs every time you restock — there's no colony to amortize it against. Availability is also less reliable: silkworm supply is somewhat seasonal and they're more fragile in transit (cold snaps and rough shipping kill them), so you can't always count on having them on hand the way you can with roaches. None of that is a knock on silkworms; it's just what a specialty feeder looks like. You budget for them as an occasional, high-value purchase — the soft feeder you buy for the picky gecko or the recovering animal — not as the cheap fuel you run the collection on.
Put together, the economics reinforce the roles: discoids are the low-cost staple you can lean on indefinitely, and silkworms are the worth-it splurge you bring in for specific jobs.
Health and safety: parasites, pesticides, and die-offs
Both feeders are safe when sourced and kept well, but each has a characteristic risk worth understanding so you can avoid it.
Pesticides are the shared danger, and it runs straight through the feeder into your gecko. Anything you gut-load a roach with, or any mulberry a silkworm eats, that carries pesticide residue ends up in the animal that eats the bug. Wash produce, buy from clean sources, and never feed wild-collected greens or mulberry of unknown spray history. This is the easiest serious mistake to make and the easiest to avoid.
Parasites are more a roach concern than a silkworm one, and mostly a function of hygiene. Captive-bred discoids from a reputable source kept in clean conditions are very low-risk; the trouble comes from filthy enclosures or, worst of all, mixing in wild-caught roaches, which can introduce parasites. The fix is simple: buy clean stock, keep the colony clean, and never add wild insects. Silkworms, being fully domesticated and captive-reared on a controlled diet, are inherently low parasite risk.
Bacterial die-offs are the silkworm's signature hazard. Silkworms are notoriously susceptible to bacterial infections (keepers run into Serratia-type crashes) that can wipe out a whole cup almost overnight, especially in damp, crowded, or dirty conditions. This is exactly why the storage rules above matter so much: keep them dry, ventilated, uncrowded, fed on fresh chow, and pull any dead or discolored worm the instant you see it. A clean, well-managed cup of silkworms is perfectly safe; a neglected, sweating one can turn fast.
The throughline for both: clean source, clean food, clean conditions. Do that and neither feeder poses meaningful risk to your gecko.
Myths worth unlearning
A handful of repeated claims cause real harm. Setting them straight:
- "Discoid roaches have a balanced or 2:1 calcium ratio." False. They're phosphorus-heavy like nearly every feeder and must be dusted with calcium. This myth, taken at face value, causes MBD.
- "Silkworms have a perfect Ca:P ratio, so you don't need to supplement." Overstated. They're better than most feeders, but still dust them. Don't bank a growing gecko's bones on it.
- "Silkworms are 60% protein, so they out-protein roaches." That's a dry-weight figure for a bug that's ~80% water. As-fed, per worm, discoids deliver more usable protein — which is exactly why discoids are the staple and silkworms are the specialist.
- "Discoids are adept climbers / will climb out of the tank." False for smooth surfaces. Adults can't scale glass or smooth plastic and don't fly.
- "Discoid is just another name for dubia." No. Discoid = Blaberus discoidalis; dubia = Blaptica dubia. Different species, and they're regulated differently (discoids are the keepable feeder in places like Florida where dubia are restricted) — so the label matters when you buy.
- "You can store live silkworms in the fridge to make them last." No — cold kills them. Keep them at room temperature.
- "One perfect feeder is enough." The single most expensive myth of all. No single feeder is complete. Variety, dusting, and gut-loading together are what keep a gecko healthy.
The verdict: it's not one or the other
So which wins the showdown? Neither — and that's the right answer, not a dodge.
Discoid roaches are your staple. They're high in protein, moderate in fat, low in chitin, easy to digest, cheap, and — the killer feature — self-breeding, so you can run a colony and feed a gecko for years at almost no ongoing cost. They're the dependable everyday backbone of the diet. Their weaknesses are real but manageable: poor calcium ratio (dust it), and a slow, shy movement style that loses some picky geckos (present them well, feed at dusk).
Silkworms are your premium specialist. They're soft, lean, hydrating, exceptionally easy to digest, and the most enticing of the two for fussy eaters — which makes them the best feeder in your toolkit for hatchlings, picky geckos, and animals recovering from illness or dehydration. Their weaknesses are also real: they cost more, they're perishable, they can't be refrigerated, and they're hard to breed, so they're a bought-as-needed feeder rather than a colony.
The best diet rotates both — a discoid staple for everyday protein, silkworms for hydration, palatability, and the vulnerable animals, everything dusted with calcium and gut-loaded, with another soft/hydrating feeder or two cycled in for breadth. By species, the rough guidance holds: leopard and tokay geckos lean on roaches as a staple with silkworms as supplement and enticement; crested and day geckos, which take a fruit-based diet plus insects, do beautifully with silkworms as the soft, easy insect option and discoids in appropriate sizes for protein.
Stop thinking of it as a fight to crown one feeder. Think of it as staffing a kitchen: you want the reliable line cook who shows up every day and the specialist you call for the delicate dishes. Keep a discoid colony running, keep fresh silkworms on hand for when you need them, dust everything, and your geckos get the best of both.
Want to go deeper on the staple side? See my complete guide to keeping and breeding discoid roaches, or browse the full exotic animal care library for more feeder and gecko guides.