Dusting & Gut Loading Insects (Mealworms, Crickets, & More)

The learning curve can be steep for new reptile keepers. You’ll not only have to learn about the basic biology of the species you select, but you’ll also have to learn about husbandry practices, figure out how to heat your pet’s habitat and get your head wrapped around the finer points of lighting the enclosure.

Unfortunately, there’s one more important thing that keepers of bug-eating reptiles must learn: How to ensure your pet is getting the necessary supplemental nutrition.

This is mainly done through dusting and gut loading insects that are being fed to your pet.

Gut loading - Bearded dragon eating cricket

As it turns out, you can’t just bring a bag of crickets home, toss them in your gecko’s enclosure and expect everything to work out well.

Instead, you must often add vitamin and mineral supplements to the insects to ensure your lizard gets everything he needs.

You must also learn how to feed the bugs properly before offering them to your pet. We’ll walk you through these issues below, which should give you a better chance of providing your lizard or snake with all of the vitamins and minerals he needs.

But we will warn you that this is a bit of a complicated issue, and you’ll have to take the things you learn here and adapt them to the specific species you keep.

In fact, you’ll likely have to adjust your practices over time and consult with your veterinarian to have the best chance of success.

The Vitamin and Mineral Needs of Reptiles

Like all other animals, insect-eating reptiles need vitamins and minerals to remain healthy.

This includes things you’ve likely heard of, such as Vitamin A, as well as substances you may not be as familiar with, such as biotin (one of the B-complex vitamins).

Different vitamins and minerals serve different biological roles.

Some, such as calcium, provide your pet with the raw material needed to make bones, while others, such as Vitamin D3 give your pet the ability to use that calcium.

Many of the insects keepers use to feed their pets are deficient in vitamins and minerals.

In fact, very few single food sources – insect or otherwise – provide all of the vitamins and minerals your lizard needs. Reptile keepers must figure out ways to provide these missing vitamins and minerals to their pet reptile.

You can feed a variety of different insects to your pet, which will help mask these deficiencies a bit. It is usually wise to supplement your pet’s food with additional vitamins and minerals too.

There are two primary ways you can do so, which we’ll explain in a minute. But first, we need to acknowledge a disappointing reality: There is very little information available regarding the precise vitamin and mineral needs of pet reptiles.

Accordingly, keepers must often extrapolate information that is available for some other animals (such as dogs, cats and feed animals, such as chickens) and devise a suitable protocol.

It is also imperative that you work in conjunction with your vet to establish an effective supplementation schedule. This is the best way to cover all your bases and give your pet the best chance at living a long, healthy life.

Adding Supplements to Bugs: Dusting Feeder Insects

The most common way keepers provide additional vitamins and minerals to their pets is through the use of a commercially manufactured vitamin and mineral supplement.

Some products contain vitamins and minerals, while others are comprised of one or the other. And some supplements only contain a single ingredient, such as calcium.

But no matter the composition of the supplement, they’re usually applied in the same basic way.

Dusting Feeder Insects: The Procedure

  1. You add a meal’s worth of crickets, mealworms or some other insect to a plastic bag or container.
  2. You then add a small amount of the supplement powder to the container.
  3. You then (gently) shake the container around, so that the supplement coats (“dusts”) the insects.
  4. You only need to add a light coating to the insects, so discard or re-collect any excess supplement in the container.
  5. You offer the coated insects to your pet as per usual.

This process is simple enough, and you’ll likely begin doing it automatically once you get accustomed to the procedure.

Most reptiles will consume dusted insects as readily as they will their un-dusted counterparts, so adding a supplement to the insects in this way doesn’t create many additional challenges.

Questions of Quantity: How Often Do You Supplement Your Lizard’s Food?

As you can see, it isn’t difficult to add a supplement to your pet’s dinner. But determining how often you should do so is another matter entirely.

Providing your pet with insufficient amounts of vitamins and minerals can cause a variety of health problems (scroll down to see some of the most common issues).

But providing excessive amounts of vitamins and minerals can also cause problems. And in many cases, the difference between sufficient and excessive amounts can be very small.

Accordingly, it is important to think carefully about the supplementation schedule you implement.

As we mentioned earlier, this is difficult, as there simply isn’t much information available regarding the vitamin and mineral needs of different reptile species.

However, many keepers have found that daily or every-other-day mineral supplementation and once-per-week vitamin supplementation works well.

Of course, there are also many keepers who employ different schedules.

Some, for example, avoid providing any supplemental vitamins at all and simply rely on dietary variety and gut-loading (discussed below) to meet their pet’s needs.

Others alternate, providing mineral supplements one day and vitamin supplements the next.

Still others utilize a combination vitamin and mineral supplement, meaning that every dusting provides both types of nutrients.

Personally, I usually add mineral supplements to every other batch of insects and a vitamin supplement to one or two feedings per week.

This has usually provided good results with the lizards I’ve most commonly kept, which includes bearded dragons, other diurnal agamids and monitor lizards.

The Most Noteworthy Vitamins and Minerals

Despite the lack of empirical data surrounding the vitamin and mineral needs of reptiles, some vitamins and minerals appear to require special attention.

We’ll discuss a few of the most notable examples below.

  • Calcium – Calcium helps reptiles build strong bones, but it is also involved in other biological processes. For example, it’s necessary for the proper function of some muscles, and it’s also important for producing eggshells. Typically, calcium is one of the most important minerals to consider when deciding on a supplementation schedule.
  • Phosphorus – Phosphorus is used in a variety of ways by your pet’s body, but fortunately, most lizards obtain plenty of the mineral from their diet. The problem is actually that you need to make sure your pet doesn’t ingest too much This can prevent your lizard from using the calcium present in his diet, so a 2:1 ratio of dietary calcium to phosphorus is typically recommended.
  • Vitamin D – Vitamin D occurs in several forms, including an “inactive” form – known as D2 – and an “active” form, which is known as Vitamin D3. Exposure to UVB wavelengths helps many reptiles convert D2 to D3, but some keepers simply provide supplemental D3 to their pet instead of providing full-spectrum lighting. Vitamin D3 helps reptiles to use the calcium contained in their diet.
  • Vitamin A – Vitamin A is involved in several ways by a lizard’s body. Among other things, it helps to keep your pet’s eyes healthy, and it appears to play a role in the development of some species too. Some keepers worry that retinol (Vitamin A) can be dangerous in large quantities, as it is a fat-soluble vitamin, so they try to use carotenoids instead, which your lizard’s body will convert to retinol as necessary. Other keepers find this unnecessary and simply administer retinol instead.

Different Species Have Different Needs

Not all insect-eating lizards are alike, and they all have different nutritional needs. Again, we simply don’t have a good understanding of the specific quantities various species require.

That said, there are a few generalizations keepers tend to make to help narrow down the needs of your specific pet:

  • Species that produce large numbers of eggs each year often require significant amounts of calcium. Building eggs is a calcium-needy activity, so bearded dragons and other prolific species often need more calcium in their diet that species who only produce a small number of eggs each year.
  • Diurnal lizards who’re not provided with full-spectrum lighting usually require supplemental Vitamin D3. Most diurnal lizards appear to require either access to sunlight or full-spectrum lighting, or supplemental Vitamin D3. Conversely, keepers who do provide proper lighting often find supplemental D3
  • Lizards that only eat a few types of prey (or one) will likely require more vitamins than species that consume a variety of foods. The greater the variety of foods that make up your pet’s diet, the less likely he is to suffer from deficiencies. This is especially true of omnivorous species, who consume a variety of insects, fruits and vegetables.

You Must Consider Your Pet’s Life Stage

It isn’t enough to simply consider the species you keep; you must also consider the sex, age and reproductive status of your pet when deciding on a supplementation schedule.

For example, young lizards who are growing rapidly often require more calcium than mature individuals of the same species.

Additionally, growing lizards may require more D3 supplementation than mature individuals, assuming they’re not provided with full-spectrum lighting.

This is especially true for large species, who must build a ton of bone from the calcium present in their diet.

In other words, a young bearded dragon or monitor lizard will likely require more calcium and Vitamin D3 than a young gecko or anole would.

Females who’re expected to produce eggs also need more calcium in their diet than non-reproductively active individuals would.

In some cases, keepers even find it helpful to provide their pet with a dish of calcium powder, which their pet can consume as necessary.

This is a particularly common practice among leopard gecko breeders.

Conversely, care must be taken to avoid over supplementing mature males with calcium. 

Liquid Supplements: A Better Option for Some Keepers?

While vitamin and mineral supplements have typically been made available in powdered form, some manufacturers have started producing liquid versions of their supplements.

In general, these types of supplements will work in the same basic way, but you’ll have to alter the method by which you administer them.

Liquid supplements aren’t easy (or practical) to apply to feeder insects, so most keepers do one of three things:

  • Administer the supplement directly to their lizard. This is the best approach to take with concentrated supplements, that need only be provided in small quantities (a drop or two). Some lizards will accept these supplements more readily than others, and those that feature a lizard-appealing flavor are usually the easiest to use.
  • Add the supplement to their pet’s food. This is not a viable option for bug-eating lizards, but if your pet consumes commercial lizard food or any type of prepared diet, it’s often easy to add the supplement directly to the food.
  • Adding the supplement to their pet’s water. If your lizard drinks readily from a water dish, you can simply add the supplement to your pet’s water bowl. The primary problem with this approach is that it can be tricky to ensure your pet is getting the proper quantity of supplement.

Tip – Always Read the Manufacturer’s Guidelines

By now, you can surely see that supplementing a pet reptile is a complicated task. So, you should always do your best to incorporate all of the valuable advice and guidance you can.

This will mean involving your vet in the process, but you should always start by consulting the supplement manufacturer’s guidelines.

All supplements are different, and the proper quantity and frequency of supplementation will vary from one product to the next.

Of course, don’t hesitate to deviate from the manufacturer’s guidelines if your vet instructs you to do so.

Similarly, make sure you adjust the supplementation schedule in response to any problems your lizard presents.

Gut Loading Insects: Feeding Your Pet’s Food Properly

“Dusting” feeder insects is likely the most common way by which keepers provide their lizard with supplemental vitamins and minerals.

However, there is another way to provide your pet with the most nutritious food items possible – it’s colloquially known as “gut loading.”

When a wild lizard catches a grasshopper, it not only gets to digest the insect and use the resources contained within its tissues; it also benefits from the foods in the insect’s digestive tract.

Think of it as Mother Nature’s way of ensuring that the lizard gets its proteins and vegetables in one convenient package.

But commercially reared feeder insects, such as the crickets or mealworms you purchase at your local pet store, are usually only fed a diet that’ll keep them alive.

This means that they’re nutritionally deficient when fed as-is.

To remedy this situation, you’ll need to feed your feeder insects a nutritious diet. This will help ensure their bellies are full of nutritious food, which will, in turn, benefit your pet lizard.

In fact, it is a good idea to purchase feeder insects at least 24 hours before you’ll need them, so you can go ahead and feed them a nutritious meal before offering them to your lizard.

Gut Loading Insects: Foods to Feed Your Feeders

Gut-loading your feeder insects is typically easy – especially for crickets, mealworms, superworms and roaches (silkworms, fruit flies and other insects often require specific foods, which are harder to provide and supplement).

It essentially requires you to provide the bugs with some type of nutritious grain, as well as an assortment of fruits and vegetables.

The carbohydrate-rich grains will help provide the insects with the calories and raw materials they need to thrive, while the fruits and vegetables will satisfy the insects’ need for water and ensure that their bellies are full of nutritious ingredients.

So, add a small dish of oats, wheat or some other grain to your insect enclosure, as well as a few orange slices and carrots.

Some keepers instead prefer to simply purchase pre-mixed insect foods, which have already been formulated to keep the insects (and your pet) healthy.

You can also use dog or cat kibble to feed the insects, and some keepers have had success using fish flakes as cricket food.

In all cases, it is wise to rotate the foods you provide to your feeder insects regularly.

This will help provide some protection against deficiencies occurring, and it’ll also help prevent problems with over-supplementation.

Just be sure to keep your insect’s food, fruits and vegetables clean and fresh, and replace them frequently to prevent molds and bacteria from contaminating them.

Health Problems Caused by Vitamin and Mineral Deficiencies

The importance of a proper supplementation schedule becomes most obvious when you consider the problems associated with vitamin and mineral deficiencies.

There are a plethora of vitamins and minerals your pet may become deficient in, but the most common issues arise in response to inadequate quantities of calcium, Vitamin D3 and Vitamin A.

Excessive phosphorus can also cause your pet to be unable to use the calcium present in his diet, which demonstrates that it is also important to avoid providing too much of a given vitamin or mineral.

Some of the most common signs and symptoms of vitamin and mineral deficiencies include:

  • Soft or malformed bones
  • Misaligned jawbones
  • Muscle twitching and tremors
  • Eye problems
  • Reproductive failures
  • Stunted growth

Additionally, vitamin and mineral deficiencies can also cause less-specific health problems, such as inappetence, lethargy and a general failure to thrive.

If you notice that your reptile is exhibiting any of these symptoms, start by assessing your husbandry procedures and look for potential problems.

Make sure that the basic habitat parameters (temperature, humidity, etc.) are all ideal and correct any problems present.

Once you’ve done this, make an appointment with your vet. Your vet will be able to determine your pet’s problem and recommend a prudent course of action.

Some of the health problems caused by vitamin and mineral deficiencies can be treated, but others are typically not easy to correct once they occur.

This illustrates the importance of implementing a proper supplementation schedule, to prevent health problems from occurring in the first place.

Why Are Insect-Eating Reptiles So Popular with Keepers?

Different people prefer keeping different types of scaly pets, but insect-eating reptiles are some of the most popular species among reptile enthusiasts.

This includes many geckos, chameleons and anoles, as well as insect-eating snakes, such as rough green snakes.

But, given the fact that insect-eating reptiles present supplementation challenges, you may wonder why these types of reptiles are so popular with keepers. 

Part of the reason for this popularity relates to the aversion many keepers have to feeding rodents, birds or other vertebrates to their pet.

Watching a monitor lizard or snake gobble down a mouse is simply not something that such keepers enjoy.

Conversely, it’s usually not difficult to watch your pet slurp down a dozen crickets or mealworms.

Insect-eating lizards are also easier to feed than herbivores in some respects.

Fruits and vegetables are certainly easier to acquire, transport, and prepare than bugs are, but balancing an herbivorous diet can be a challenging task.

Insects are also a pretty affordable food source for many reptiles.

You can likely keep a bug-eating leopard gecko fed for a few dollars a week but providing a large python or monitor lizard with sufficient food will cost much more money.

Ultimately, this leads many reptile enthusiasts to select insect-eating species, despite some of the supplementation challenges they present.


Insects represent a convenient and affordable food source for many reptiles, but as you now know, you must do a few things to ensure they provide your pet with the nutrition he requires.

This means not only gut-loading your feeder insects but implementing a supplementation plan to help further avoid deficiencies.

Just remember to discuss the issue with your vet and take clues from others who keep the same species you do, and don’t be afraid to make adjustments to your dusting or cricket-feeding practices if problems arise.