Gut Loading Feeder Insects: The Complete Guide

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Gut loading is the practice of feeding insects a nutrient dense diet for a set period before they become food for a pet lizard. The idea is simple. A cricket or roach still carries its last meal in its gut.

A calcium rich last meal passes that calcium on to the lizard that eats it.

Most feeder insects arrive from the store already low in calcium. Gut loading is one of two main tools keepers use to fix that gap. The other is calcium dusting.

This guide covers what to feed, how long to gut load, and how the two methods compare.

What Gut Loading Actually Does

Crickets, dubia roaches, and mealworms are naturally low in calcium. They also run high in phosphorus. Left alone, a cricket has a calcium to phosphorus ratio well under 1 to 1, sometimes as low as 0.12 to 0.19 to 1.

Gut loading corrects that ratio from the inside. Keepers feed the insects a calcium rich diet, such as Repashy Bug Burger, for a day or two. The insects digest that food and store the calcium in their gut and tissue.

The lizard then eats an insect carrying far more calcium than it would hold otherwise. Research on crickets backs this up. A high calcium diet fed for up to 48 hours pushed cricket calcium to phosphorus ratios near 2 to 1.

Dubia roaches show a similar pattern. One veterinary study found untreated adult roaches carried an inverse ratio around 0.26 to 1.

Roaches fed a diet that was 8.3 percent calcium for 24 hours reached ratios above 1 to 1. Some groups climbed past 5 to 1.

Why Calcium to Phosphorus Balance Matters

Reptile nutritionists generally aim for a dietary calcium to phosphorus ratio between 1 to 1 and 2 to 1. Calcium is needed for muscle function and nerve signaling. Below that ratio, a lizard’s body starts pulling calcium out of its own bones to keep blood calcium stable.

Over months, that borrowing shows up as metabolic bone disease. Signs include a soft or swollen jaw, bowed limbs, tremors, and reluctance to move.

Gut loading and dusting both exist to prevent this outcome. A lizard already showing these signs needs a reptile veterinarian, not just a diet change.

How to Gut Load Crickets

Crickets are the most common feeder insect. They are also fast eaters. Gut loading them is straightforward if you keep a feeding tub running at all times.

• Keep crickets in a ventilated tub, separate from your lizard’s enclosure, with egg cartons for hiding and climbing.
• Offer a calcium rich commercial gut load diet as the only dry food. Do not mix it with low calcium scraps.
• Provide moisture through a damp paper towel, a shallow dish of chopped greens, or a commercial hydration gel made for insects. Avoid a plain water dish, which can drown small crickets.
• Hold the crickets on that diet for at least 24 hours, and ideally closer to 48 hours, before feeding them out.
• Feed the crickets to your lizard within a few hours of pulling them off the gut load diet. The calcium boost fades as the insect’s gut empties.

See our full cricket care and feeding guide for tub setup. It also covers how to keep crickets alive between purchases, so you always have a fresh batch ready to load.

Gut Loading Dubia Roaches

Dubia roaches move slower than crickets and hold up better in storage. That makes them easier to gut load well. One study found dubia roaches held elevated calcium stores for up to 72 hours after loading, even while fasting.

Crickets typically hold their calcium boost for far less time. This staying power matters in practice. A dubia colony, such as Josh’s Frogs Medium Dubia Roaches (live), fed a consistent high calcium diet stays reasonably well loaded, even if you cannot feed out insects the same day.

Not every commercial diet works, though. The same study found a low calcium product failed to correct the roaches’ natural calcium deficit. A diet around 8 percent calcium corrected the deficit within 24 hours.

Keep a dedicated dubia colony on a permanent calcium forward diet. Use a commercial gut load or high calcium roach chow as the main food. Add vegetable scraps only as a minor supplement.

What to Feed Crickets and Other Feeders

The best gut load diets share one trait. Calcium content sits in the range of 8 to 9 percent, usually from calcium carbonate. They also carry enough moisture and general nutrition to keep the insects alive and eating.

Skip citrus fruit, onion, and anything salted or sugared. These can sicken the insects and add little nutritional value.

What to feed crickets during the loading window matters more than what you feed them day to day. That final meal is what the lizard actually receives.

Several commercial gut load diets have shown measurable calcium gains in published testing. The products that worked all listed calcium near 8 percent on the label, while a low calcium commercial chow tested alongside them did not correct the deficit. Read the guaranteed analysis on the bag rather than the marketing, and our feeding and husbandry supplies page covers what else a feeder colony needs.

How Long to Gut Load

Timing depends on the insect species. Crickets need roughly 48 hours on a high calcium diet to reach their best ratio. A shorter 24 hour load still helps.

Mealworms respond faster. A 24 hour load raises their calcium to phosphorus ratio noticeably. Extending to 48 or 72 hours only adds a small further gain.

Dubia roaches reach a strong ratio within 24 hours and hold it far longer than crickets or mealworms.

Avoid loading any insect for much longer than 72 hours. Insects fed the same calcium heavy diet for too long start eating less of it. The calcium gain can drop compared to a shorter, well timed load.

Gut Loading vs Dusting

Gut loading and calcium dusting solve the same problem from different directions. Most keepers should use both rather than choosing one.

Dusting means coating feeder insects in calcium powder right before feeding. The lizard eats the powder along with the insect.

A peer reviewed comparison found dusted crickets held a ratio above 1 to 1 for at least 5.5 hours after dusting. That matched or beat gut loading alone over a similar window.

Dusting delivers a fast, reliable calcium hit right at feeding time. Gut loading builds a better insect from the inside over a day or two.

Use a calcium dusting powder on the schedule your species guide recommends. Run your feeder colony on a calcium forward gut load diet as the everyday baseline, not as an occasional extra step.

Species with high calcium needs, including growing juveniles and gravid females, often need both methods used consistently. Check our supplement and dusting schedule guide for a species specific breakdown.

Common Gut Loading Mistakes

The most common error is loading insects on the wrong food. Bran and potato peels do little to shift the ratio, no matter how long the insects sit on them.

The second error is timing. Feeding insects out right after buying them, with no loading period at all, skips the entire benefit. Waiting more than three days on the same diet can undo some of that early gain.

The third error is treating gut loading as a full replacement for dusting. A well loaded insect still benefits from a light coat of calcium powder just before feeding. This matters most for species prone to metabolic bone disease, such as bearded dragons and green iguanas.

Frequently Asked Questions

What does gut loading mean for feeder insects?

It means feeding crickets, roaches, or other feeder insects a calcium rich diet for a day or two before they are fed to a lizard. The insect carries that nutrition in its gut and passes it on to the reptile that eats it.

How long should you gut load crickets before feeding them out?

Aim for 24 to 48 hours on a high calcium diet. Longer than 72 hours can lower the calcium gain, since the insects grow tired of the food.

Is gut loading better than calcium dusting?

Neither replaces the other. Published testing found dusting gives an equal or better short term calcium boost, while gut loading raises the insect’s overall nutrition. Most keepers use both.

What is the best gut load diet for dubia roaches?

A commercial diet around 8 percent calcium, such as a high calcium dubia formula, corrected the natural calcium deficit in roaches within 24 hours in published testing. A low calcium commercial diet did not.

Can you gut load insects for too long?

Yes. Insects held on the same calcium heavy diet beyond about 72 hours tend to eat less of it. That can lower the calcium gain compared to a shorter loading period.

Do all feeder insects need gut loading?

Any insect fed to an insectivorous or omnivorous lizard benefits from it. Store bought insects are naturally low in calcium. Check our guide to what lizards eat for how feeder insects fit into a full diet.