Katydids, Springtails, or Roaches: What Leopard Geckos Actually Thrive On

I've fed a lot of leopard geckos over the years, and the question in this article's title is the one that trips up almost every new keeper: katydids, springtails, or roaches — which one do leopard geckos thrive on? The honest answer is that this is a trick question, because the three things being compared aren't really the same kind of thing at all. One is a genuine staple feeder. One is a cleanup crew that belongs in your substrate, not your gecko's mouth. And one is a wild insect you should mostly stay away from.

A lot of the writing out there treats these three as interchangeable items on a menu, ranks them by protein percentage, and calls it a day. That framing is wrong, and following it leads people to underfeed their gecko while sprinkling tiny soil bugs in the tank thinking they're "supplementing the diet." So let me set the record straight, with real numbers and the reasoning behind them. By the end you'll know exactly what to put in the feeding dish, what to put in the soil, and what to leave in the field.

Here's the verdict up front so nothing's ambiguous: leopard geckos thrive on a roach (or other clean, gut-loaded staple insect) as the core of the diet, dusted with calcium. Springtails belong in a bioactive substrate as a cleanup crew, not in the food dish. Katydids are a no. Everything below is the why.

What leopard geckos actually eat

Leopard geckos (Eublepharis macularius) are insectivores — strict ones. They evolved across the rocky, arid scrublands of Afghanistan, Pakistan, and northwestern India, where they hunt at dusk and night, ambushing whatever appropriately sized invertebrate wanders past: crickets, beetles, spiders, larvae, the occasional small scorpion. They are not omnivores. Their digestive tract is built to process whole insect prey, and it cannot extract meaningful nutrition from plant matter. This is the first fact that has to anchor everything else: you cannot feed a leopard gecko fruit, vegetables, salad, or pellets and expect it to live well. It eats bugs, or it slowly declines.

That biological reality is the whole reason this article matters. Because the gecko gets everything — protein, fat, moisture, vitamins, minerals — from insects and the supplements you add to those insects, the quality and balance of those insects is, quite literally, the gecko's entire nutritional world. There's no second food group to make up the difference. Get the feeders right and the gecko thrives for fifteen, even twenty years. Get them wrong and you get the slow, preventable diseases that fill reptile-vet appointment books: metabolic bone disease, obesity, fatty liver, impaction.

In captivity, the practical diet boils down to a small set of farmed feeder insects:

• ◆Staples — fed as the everyday base of the diet: roaches (discoid, dubia, red runner) and crickets.
• ◆Rotational variety — fed regularly but not as the whole diet: black soldier fly larvae (sold as "calci-worms" or "Phoenix worms"), silkworms.
• ◆Treats — fed occasionally, for hydration or to fatten up a thin animal: hornworms (mostly water), waxworms and superworms (high fat).
• ◆Not feeders at all — springtails (cleanup crew) and wild-caught insects like katydids (avoid).

The art of feeding a leopard gecko isn't finding one magic bug. It's building a staple-plus-rotation pattern and supplementing it correctly. So let's take the three contenders in the title one at a time and put each in its real role.

Roaches: the true staple leopard geckos thrive on

If you only take one thing from this guide, take this: a gut-loaded, calcium-dusted roach is the best everyday food you can give a leopard gecko. Roaches are where the word "thrive" actually applies.

Among feeder roaches, three species come up constantly — dubia (Blaptica dubia), red runners (Shelfordella lateralis), and discoids (Blaberus discoidalis). They're all good. I lean toward discoid roaches for most keepers, and especially for anyone in Florida, where dubia are restricted but discoids are an accepted feeder. Discoids are soft-bodied, low in chitin (the hard structural material in an insect's shell), and — a detail that saves enormous frustration — they can't climb smooth vertical surfaces like glass or smooth plastic. A loose roach in a smooth-walled enclosure or feeding cup stays put instead of scaling the walls and escaping into your house. (You'll occasionally see this claimed the other way around; it's wrong. Adult discoids genuinely can't grip smooth glass.)

Why roaches earn the staple slot

The case for a roach staple rests on four things, and none of them is "highest protein number on a chart":

1. ◆A digestible, soft body. Low chitin means the gecko's gut breaks the feeder down easily, with less risk of impaction than hard-shelled prey like adult mealworms or beetles. Soft and digestible matters more for a small lizard than a marginally higher protein percentage.
2. ◆They gut-load beautifully. A roach that has spent a day or two eating leafy greens, squash, and a quality dry chow becomes a nutrient package — and what the roach ate is what your gecko eats. Roaches hold gut-load well and stay full longer than crickets. This is the real lever on feeder quality, and roaches respond to it better than almost anything else.
3. ◆They're calm, quiet, and clean. Crickets stink, chirp at 2 a.m., jump out of the dish, and die constantly. Roaches do none of that. A roach colony or even a holding tub is nearly odorless and low-maintenance, which means you are more likely to keep feeders in good condition, which means your gecko eats better. Husbandry that's easy to do correctly is husbandry that actually gets done.
4. ◆They live a long time as feeders. A tub of roaches survives for weeks on a little warmth, moisture, and food, so you buy less often and waste less. That also means you can keep them well-fed and ready to gut-load on demand rather than scrambling.

The roach nutrition reality — and the calcium myth you must ignore

Here are honest, approximate, as-fed figures for a discoid roach. Treat these as ballpark — real values shift with diet, life stage, and source — but the relationships are what matter:

• ◆Protein: ~20% — high, and exactly what a growing insectivore needs.
• ◆Fat: ~6–7% — moderate, enough for energy without driving obesity. This is the balance that makes roaches a staple rather than a treat: contrast that with a waxworm at ~20%+ fat, which is dessert.
• ◆Moisture: ~60% — solid hydration as part of a meal.
• ◆Chitin: low — easy to digest.

Now the part the source material gets dangerously wrong, and that I want to correct in plain language: roaches do NOT have a "robust" or "favorable" calcium-to-phosphorus ratio. This is one of the most repeated falsehoods in the feeder-insect world. The truth is that nearly every feeder insect — roaches absolutely included — is phosphorus-heavy. They contain far more phosphorus than calcium, often by a ratio of roughly 1:3 to 1:9 in the wrong direction.

Why does that matter? Because calcium and phosphorus work against each other in the body. When there's too much phosphorus relative to calcium, the gecko's body can't use the calcium it does get — it pulls calcium out of the bones to balance the blood, and over time the skeleton softens and deforms. That's metabolic bone disease (MBD), and it is the number-one preventable killer of pet leopard geckos. It comes from exactly this: a phosphorus-heavy insect diet without calcium correction.

So here is the rule that is non-negotiable, no matter how well you gut-load: you must dust roaches (and every staple feeder) with a calcium supplement before feeding. Gut-loading improves the overall nutrition; dusting is what actually fixes the calcium-to-phosphorus imbalance. They are two different jobs and you need both. More on the exact supplement schedule below — but understand now that "my roaches are gut-loaded so I don't need calcium powder" is the belief that lands geckos at the vet with bent legs and a rubber jaw.

When you're ready to start, a healthy, well-started colony or feeding batch makes all the difference — All Angles Creatures stocks discoid roaches sized for everything from hatchling geckos to adults, which is where I'd point a new keeper before they go down the wild-insect or grocery-store rabbit hole. If you want to breed your own and never buy feeders again, I've written a full discoid roach keeping and breeding playbook that covers the colony from setup to harvest.

Springtails: cleanup crew, not a food source

Now the part where the conventional internet article goes off the rails. You'll read that springtails (Collembola) are a "supplemental food source" for leopard geckos, that they're "high in protein," that they "help meet hydration needs." Let me be blunt and clear, because this is the most important correction in the whole guide: springtails are not a meaningful food source for a leopard gecko. They are a cleanup crew.

Why springtails can't feed an adult leopard gecko

Look at the size mismatch. A springtail is 1–3 millimeters long — smaller than a grain of rice, often smaller than a pinhead. An adult leopard gecko is a 7 to 10 inch lizard that hunts prey sized to the gap between its eyes — roughly a 1/2-inch to 3/4-inch insect. Asking a leopard gecko to live on springtails is like asking a grown adult to get their daily calories by picking individual sesame seeds off a plate. The math simply doesn't work. The caloric contribution of a springtail to a leopard gecko's diet rounds to zero.

Even setting size aside, leopard geckos hunt by detecting movement and lunging at discrete, visible prey. A swarm of near-invisible specks in the soil isn't something a gecko meaningfully hunts and eats as a meal. The occasional springtail a gecko might lick up while grabbing a roach is incidental — it's not nutrition you can plan a diet around.

So when a source lists springtails as a feeder ranked by protein percentage next to roaches, it's making a category error. The protein percentage of a springtail is irrelevant to a leopard gecko for the same reason the protein percentage of a single ant is irrelevant to a wolf. It's not the protein content that disqualifies it — it's that it's not food at this scale.

(For the record: springtails are a real feeder — for tiny animals. Dart frog froglets, very small fish fry, juvenile mantises, and the like genuinely eat springtails as food. That's a real and valuable use. It's just not leopard geckos.)

What springtails are actually for

Here's where springtails earn their place in a leopard gecko keeper's world: the bioactive enclosure.

A bioactive setup is an enclosure built on a living substrate — a real soil mix instead of paper towels or tile — that maintains itself biologically rather than needing you to scoop every dropping. The system works because of a "cleanup crew": tiny invertebrates that live permanently in the substrate and eat the waste. Springtails are the smaller half of that crew (isopods are the larger half). Springtails specifically eat:

• ◆Mold and fungus — they graze it before it can bloom, which is why a bioactive tank with a healthy springtail population almost never gets a mold outbreak.
• ◆Decaying plant matter — dead leaves, bits of sphagnum, organic debris.
• ◆Feeder leftovers and feces — the bits of roach a gecko leaves behind, and broken-down waste.

In other words, springtails turn waste into healthy soil and keep the substrate from going foul. They're a janitorial workforce living under your gecko's feet. A pot of them costs a few dollars and they reproduce on their own indefinitely as long as the substrate stays humid in a corner. This decomposer role isn't reptile-hobby folklore, either — it's basic soil ecology. As Penn State Extension notes, springtails feed on fungi, mold, algae, and decaying plant material, which is exactly the behavior that makes them so useful in a bioactive enclosure and so useless as a meal for a 9-inch lizard.

So the correct mental model is: springtails go in the substrate to keep the enclosure clean. Roaches go in the dish (dusted) to feed the gecko. Two completely separate jobs. Anyone telling you to "feed your gecko springtails for protein" has confused the cleanup crew for the meal.

How a bioactive setup works, briefly

Since springtails only make sense in this context, here's the quick version of how the system fits together for a leopard gecko:

• ◆Substrate: a draining, semi-arid bioactive mix (leopard geckos are desert animals — you want a soil/sand blend that holds a little moisture in a lower layer but stays dry on top, not a wet tropical mix). A drainage layer underneath prevents waterlogging.
• ◆Cleanup crew: springtails plus a desert-tolerant isopod species (like Porcellio or Armadillidium varieties). They establish over a few weeks and self-sustain.
• ◆A humid retreat: even in a desert bioactive build, you keep one corner or hide damp. That's where the springtails thrive and where the gecko goes to shed.
• ◆The payoff: waste breaks down in place, mold is grazed away, and you spot-clean far less. The crew quietly recycles everything.

A bioactive build isn't mandatory — plenty of healthy geckos live on tile or paper towel with manual cleaning. But if you go bioactive, springtails are essential infrastructure. That's their role: infrastructure, not food.

Katydids: a wild insect to avoid

The third contender is the easiest to rule out. Katydids are those leaf-shaped, long-antennaed relatives of grasshoppers and crickets you hear singing in summer. Can a leopard gecko physically eat one? Sure. Should you feed them? No. And the reasons are about safety, not snobbery.

Katydids aren't a farmed feeder

There is no meaningful commercial supply of clean, captive-bred katydids the way there is for crickets, roaches, or BSFL. They aren't farmed at scale as feeders. So in practice, "feeding your gecko katydids" means one thing: catching wild ones. And wild-caught insects are the single biggest avoidable risk in this entire hobby. Here's what you're rolling the dice on every time you toss a field-caught bug into the tank:

• ◆Pesticides and herbicides. A katydid from anywhere near lawns, gardens, parks, or farmland has likely walked on or eaten treated vegetation. Those chemicals concentrate in the insect, and then in your gecko. This kind of poisoning can be fatal and there's often no way to know until the animal is sick.
• ◆Internal and external parasites. Wild insects routinely carry parasites that farmed feeders don't. Feed enough wild bugs and you eventually introduce a parasite load your gecko has to fight off — weight loss, lethargy, digestive trouble, and a vet bill to deworm.
• ◆Misidentification. Katydids look a lot like other insects, and the wild is full of things that are toxic to reptiles — certain grasshoppers, fireflies (which contain compounds lethal to many reptiles), blister beetles, and more. One wrong grab can kill a gecko. Confidently telling a katydid from a look-alike at dusk in the field is harder than it sounds.

There's no upside to justify the risk

The thing is, even if katydids were perfectly clean, they wouldn't do anything for your gecko that a gut-loaded roach doesn't do more safely. They're "high protein, moderate fat" — which describes a roach too, except the roach is farmed clean, gut-loaded on your schedule, dusted with calcium, and carries none of the wild risks. There's no nutrient in a katydid that's missing from a properly managed staple. So you'd be taking on real, potentially fatal risk for zero benefit.

The only honest framing for katydids is the same one I'd give for any wild insect: a novelty to avoid. If you want dietary variety — and variety is genuinely good — get it from other farmed feeders (BSFL, silkworms, the occasional hornworm), not from the backyard. The rule is simple and absolute: never feed wild-caught insects. Katydids are just one example of a much bigger "don't."

Comparison table: the three feeders side by side

Here's the head-to-head — but read it with the framing above in mind, because the most important columns are the last two, not the protein number. Ranking these three purely by macros is exactly the mistake that started this whole confusion.

The table makes the point visually: these aren't three feeders to rank. One feeds the gecko, one cleans the floor, and one is a hazard. The protein-percentage rows are almost a distraction — note that springtails' protein is marked irrelevant not because it's low but because the animal is too small to be food, and katydids' respectable protein doesn't save them from the risk column.

Calcium, phosphorus, and supplementation — the part that prevents disease

I've mentioned the calcium-to-phosphorus problem twice already because it's that important. Here's the full picture, because supplementation done right is what separates a gecko that thrives for two decades from one that develops MBD in its first year.

The ratio problem in plain terms

The target calcium-to-phosphorus ratio in a reptile's overall diet is roughly 2:1 (twice as much calcium as phosphorus) — sometimes cited as the ideal range of 1.5:1 to 2:1. Feeder insects come in at the opposite of that: phosphorus-heavy, often inverted. So left uncorrected, an insect-only diet drives the gecko toward calcium deficiency no matter how "healthy" the bugs look. The body responds to low blood calcium by leaching it from the skeleton — and that's metabolic bone disease: soft bones, swollen or bent limbs, a rubbery jaw, tremors, spinal kinks. It is common, it is debilitating, and it is almost entirely preventable.

The two-tool fix: gut-load AND dust

You correct the diet with two distinct, non-interchangeable tools:

1. ◆Gut-loading improves the overall nutrition the insect carries — vitamins, some minerals, moisture, the general quality of the package. It nudges things in the right direction but does not fully fix the calcium-to-phosphorus ratio on its own.
2. ◆Dusting is the actual ratio correction. You toss the feeders in a calcium powder right before feeding so the gecko swallows supplemental calcium with the bug. This is what tips the balance back toward 2:1.

Do both. Skipping dusting because "they're gut-loaded" is the single most common cause of preventable MBD I see.

A practical supplement schedule

Supplements come in three types, and you rotate them:

• ◆Plain calcium (no D3): calcium carbonate powder, no vitamin D3. Use this on most feedings — for many keepers, this is the everyday dust.
• ◆Calcium with D3: vitamin D3 lets the body absorb calcium. Geckos make their own D3 in skin exposed to UVB light; if you don't provide UVB lighting, you must supply D3 in the diet. Use calcium-with-D3 a couple of times a week (and don't massively overdo D3, since it's fat-soluble and accumulates).
• ◆Multivitamin: a reptile multivitamin (covering vitamin A and others) dusted once a week or so rounds out the micronutrients gut-loading doesn't cover.

A simple, safe rotation that works for most adult leopard geckos:

• ◆Most feedings: dust with plain calcium.
• ◆~2x per week: dust with calcium + D3 (lean more on this if you don't run UVB).
• ◆~1x per week: dust with a reptile multivitamin instead.

Growing juveniles, who are building skeleton fast, lean toward calcium at nearly every feeding. Whatever the exact cadence, the principle holds: calcium at most meals, D3 and multivitamin layered in on a schedule, never zero. For the underlying nutrition and disease side of this, the Merck Veterinary Manual's reptile nutrition section is an authoritative, non-commercial reference worth bookmarking.

Gut-loading: feeding the feeders right

Gut-loading is exactly what it sounds like: loading the feeder insect's gut with good nutrition shortly before it becomes a meal, so the gecko eats a well-fed bug instead of a starved one. It's the highest-leverage habit in feeder management, and it's easy.

The timing: gut-load for 24 to 48 hours before feeding off. That window is long enough for the insect to fill up on good food but short enough to avoid the food spoiling or the bug starving. Loading insects for far longer than that just invites mold in the feeder tub and degrades quality.

What to feed the feeders:

• ◆Fresh produce and leafy greens: carrots, squash, sweet potato, dandelion greens, collard greens, mustard greens, a little apple. The dark leafy greens are especially good because they bring some calcium of their own into the package.
• ◆A quality dry base / commercial gut-load: a dedicated dry feeder chow or gut-load product provides steady protein and is the backbone of the feeder's diet between produce.
• ◆Clean hydration: moisture from the produce, or water crystals/gel. Never an open dish of standing water — small feeders drown in it.

What to avoid feeding the feeders: anything you wouldn't want passed up the chain — heavy citrus, onion, garlic, anything salty, oily, processed, or possibly treated with pesticide. Wash produce first.

The mental model that makes this click: the roach is a delivery vehicle. Whatever you load it with is what your gecko receives a day later. Load it with squash and greens and you're delivering vitamins and moisture; load it with nothing and you're delivering an empty shell. Combine good gut-loading with correct calcium dusting and you've covered the entire nutritional job that feeders have to do.

Building variety around the staple

A roach staple is the spine of the diet, but it shouldn't be the whole diet. Variety does two things: it covers small nutritional gaps no single feeder fills, and it keeps a gecko interested (geckos do get bored and can turn picky on a monotonous diet). The key is that variety comes from other farmed feeders — never from the backyard. Here's how the legitimate rotation feeders fit around the staple, and which slot each one belongs in:

• ◆Black soldier fly larvae (BSFL) — sold as "calci-worms," "Phoenix worms," or "repti-worms." These are the one genuinely notable exception to the phosphorus-heavy rule: BSFL actually carry a favorable calcium-to-phosphorus ratio naturally, because they're rich in calcium. That makes them a fantastic rotational feeder and a real ally against MBD. They're small and soft, so they suit geckos of most sizes. I rotate these in regularly — they're the closest thing to a "free calcium boost" in feeder form, though I still keep up normal dusting on the staple roaches.
• ◆Silkworms — soft-bodied, high in moisture and protein, low in fat, and easy to digest. An excellent rotational feeder and a good choice for a gecko that needs gentle, nutritious food. The catch is they're more perishable and pricier than roaches, so they're a rotation item, not a base.
• ◆Hornworms — these are mostly water (often 80%+ moisture). That makes them a great hydration treat, especially for a gecko that's a bit dehydrated or constipated, but they're far too low in protein to build a diet on. Offer occasionally, watch the size (they grow fast), and treat them as a juicy snack, not a meal.
• ◆Waxworms and superworms — the dessert tier. Both are high in fat (waxworms especially, often 20%+), which makes them useful for fattening up a thin, recovering, or eggbound female — and a fast road to obesity if they become routine. Superworms also have a hard head capsule and tougher shell, so for leopard geckos they're an occasional treat, not a staple. Feed these sparingly and deliberately.
• ◆Crickets — worth naming as the other legitimate staple alongside roaches. Nutritionally they're fine (moderate protein, low-ish fat), and a gecko hunting jumpy crickets gets good enrichment. The downsides are practical: they smell, they're noisy, they die quickly, and they escape. Many keepers (me included) prefer roaches precisely to avoid those headaches, but a gut-loaded, dusted cricket is a perfectly good staple if you'd rather keep them.

A simple, healthy pattern for an adult: roaches (or crickets) as the everyday base, BSFL and silkworms rotated in across the week for balance, hornworms as an occasional hydration treat, and waxworms/superworms reserved for special cases. That rotation, all dusted appropriately, beats any single feeder — and notice that every item on the list is farmed. The variety comes from the supplier, not the field.

Reading your gecko: signs the diet is working (or isn't)

The best feeding plan in the world still needs you to watch the animal. Leopard geckos are stoic and hide illness well, so you read their condition through a few reliable signals:

• ◆The tail. A leopard gecko's tail is its fat reserve and its single best health gauge. A healthy tail is plump and roughly as wide as the neck. A thin, shriveled tail means underfeeding, illness, or parasites. A tail so swollen it dwarfs the body means overfeeding — back off frequency and lay off the fatty treats.
• ◆Body condition. You want a gecko with a rounded belly and no visible hip bones or spine ridges (too thin), but also without rolls of fat or fat pads bulging behind the front legs (too fat). Lean-but-rounded is the target.
• ◆Appetite and energy. A sudden refusal to eat, lethargy, or hiding more than usual is a flag. Some appetite dip is normal around shedding or seasonal cooling, but a persistent hunger strike warrants attention.
• ◆Signs of metabolic bone disease. Catching MBD early matters. Watch for: a soft or rubbery jaw, swollen or bowed legs, difficulty lifting the body off the ground (a "splayed" walk), tremors or twitching, spinal kinks, and repeated trouble shedding. Any of these means the calcium/D3 side of the diet has failed and you need a reptile vet promptly — early MBD is treatable, advanced MBD often isn't.
• ◆Stool and shedding. Firm, regular droppings and clean, complete sheds both signal good nutrition and hydration. Runny stool, undigested feeder parts, or stuck shed (especially on toes) point to husbandry or diet problems worth chasing down.

The throughline: feed the schedule, but adjust to the animal. The calendar tells you roughly how often; the tail and body condition tell you whether it's actually working. When something looks off and a husbandry tweak doesn't fix it within a week or two, an experienced reptile vet is the right call — not another change to the feeder rotation.

Feeding schedule and portions by age

How much and how often changes a lot across a leopard gecko's life. The single biggest swing is frequency: babies eat constantly to grow, adults eat modestly to avoid getting fat.

Hatchlings and juveniles (0–10 months)

• ◆Frequency: daily. Young geckos are growing fast and need steady protein and calcium.
• ◆Portion: offer as many appropriately sized feeders as they'll enthusiastically eat in about 10–15 minutes — often in the range of several small feeders per session. A loose guide is roughly two feeders per inch of the gecko's length.
• ◆Feeder size: small. Hatchling-appropriate roach nymphs or small crickets — nothing wider than the space between the eyes.
• ◆Supplements: calcium at nearly every feeding; D3 and multivitamin layered in per the schedule above. Skeleton-building is the priority at this age.

Subadults (10–12+ months)

• ◆Frequency: every other day as growth slows.
• ◆Portion: a few appropriately (and now larger) sized feeders per session.
• ◆This is a transition stage — ease off frequency gradually rather than dropping suddenly, letting the gecko's metabolism adjust.

Adults (12+ months)

• ◆Frequency: 2–3 times per week. Adults are prone to obesity, and overfeeding is a genuine health risk — fatty liver disease is real in pampered captive geckos.
• ◆Portion: a small handful of appropriately sized feeders per session — for many adults, somewhere around 4–6 staple feeders, adjusted to body condition.
• ◆Watch the tail. A leopard gecko stores fat in its tail. A healthy tail is plump and roughly as wide as the neck — not skinny (underfed) and not so fat it bulges grotesquely (overfed). The tail is a better feeding gauge than any chart.

The universal rules across all ages

• ◆Feeder size: never wider than the gap between the gecko's eyes. This single rule prevents both choking and impaction. When unsure, size down.
• ◆Hydration: always provide a shallow dish of clean water, even though much hydration comes from food.
• ◆Watch the animal, not just the calendar. Lethargy, weight loss, a thinning tail, or refusing food are signals to reassess — and a sudden change warrants a reptile vet, not just a schedule tweak.

Common myths, corrected

A lot of bad advice circulates about feeding leopard geckos. Here are the ones most relevant to this article, set straight:

• ◆Myth: "Springtails are a supplemental food source for leopard geckos." No. They're a substrate cleanup crew, far too small to feed a gecko. Their job is eating mold and waste in a bioactive setup. (Corrected at length above.)
• ◆Myth: "Roaches have a good calcium-to-phosphorus ratio, so you can skip calcium powder." Flatly false and dangerous. Roaches, like nearly all feeders, are phosphorus-heavy. You must dust with calcium regardless of how well you gut-load.
• ◆Myth: "Discoid roaches climb glass, so you can't use them loose." Wrong — adult discoids can't grip smooth vertical surfaces. That's actually one of their best traits as feeders.
• ◆Myth: "Discoids are Blaptica dubia." Different species. Discoid roaches are Blaberus discoidalis; dubia are Blaptica dubia. Both are good feeders, but they're not the same bug — and discoids are the ones legal in places like Florida where dubia are restricted.
• ◆Myth: "Wild katydids/grasshoppers are a free natural feeder." No. Wild insects carry pesticide residue, parasites, and look-alike toxicity risk. Never feed wild-caught insects, full stop.
• ◆Myth: "Mealworms (or any one bug) can be the whole diet." Variety matters, and hard-shelled adult mealworms in particular are high-chitin and impaction-prone as a sole diet. Build around a soft staple roach and rotate.
• ◆Myth: "Leopard geckos can eat some fruit or veg for variety." No — they're strict insectivores and can't digest plant matter. The plants go into the feeders (gut-loading), never directly into the gecko.
• ◆Myth: "Freeze-dried insects are just as good and easier." Leopard geckos hunt by movement and largely ignore motionless prey; freeze-dried feeders also lose moisture and some nutrition. Live, gut-loaded feeders are the standard for a reason.

The verdict

So — katydids, springtails, or roaches? The question only looks like a three-way comparison. Line the three up honestly and they fall into three completely different bins:

• ◆Roaches are the staple. A gut-loaded, calcium-dusted roach — discoid being my pick for its soft body, low chitin, gut-loading quality, and the fact that it can't climb out of a smooth dish — is the everyday food a leopard gecko genuinely thrives on. Build the diet's spine here.
• ◆Springtails are cleanup crew, not food. At 1–3 mm they can't feed a gecko, and that's fine, because that was never their job. Their job is living in a bioactive substrate eating mold and waste. Put them in the soil, not the dish.
• ◆Katydids are a no. As a wild insect they carry pesticide, parasite, and toxic-look-alike risk with zero upside over a clean farmed feeder. Avoid wild-caught insects entirely.

Put it all together and the real care plan is simple: a clean, gut-loaded roach staple, dusted with calcium at most meals (with D3 and a multivitamin rotated in), fed daily to babies and a few times a week to adults, sized never larger than the space between the eyes — with springtails quietly maintaining the substrate underneath and the backyard bugs left exactly where they are. Do that, and "thrive" stops being a marketing word and starts being what your gecko actually does, for fifteen or twenty years.

Want to go deeper on the staple feeder itself? See my full discoid roach keeping and breeding playbook, and browse the rest of the exotic animal care library for more species and feeder guides.