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Image by Shelley Pauls


Updated: Aug 4, 2022

An explanation of what happens to your crested gecko food over time and why you should not feed it to your feeders...

"My crested gecko doesn't eat all of its food so what should I do with the leftover uneaten food in the dish? I don't want to waste it..."
“Just throw your old gecko food dishes with uneaten food into your feeder bins! It's a great gutload!”

So many times we read this scenario on social media and though yes it may seem like a convenient way to make use of your old food & feed your buggies all at once I can assure you it is not beneficial at all. To better explain this we have to explain a few other things first, like what is gut loading, what is harmful to feeders, and what happens to food when it is left out over long periods of time. We will also discuss some of the ways to eliminate and avoid food waste! So let's go on and adventure shall we!

What Exactly Is Gutloading & Why Is It Important?

(The following Is Credited to

Gut loading is the process by which an animal's prey is raised and fed nutritious foods with the intention of passing those nutrients to the animal for which the prey is intended. This term is used most often in reference to the preparation of insects, such as crickets and mealworms, or mice which are used as food for reptile pets. Insects that are raised commercially for the pet trade are themselves of little nutritional value. By providing the prey animals with a high quality diet prior to feeding, they become a more nutritious meal for the predator.

Gut loading can be accomplished by providing fruits, vegetables, or a nutritionally complete manufactured diet. Several commercial products are available and are fortified specifically for gut loading. These products often include varying combinations of carbohydrates, fats, proteins, vitamins, minerals, and dietary fiber.

Gut loading is considered most important if the primary source of nutrition is from insects. This is due to the fact that commercially raised insects are very nutrient poor compared to wild counterparts. This is especially true of vitamin A, among many other nutrients.

Gut loading is designed to increase the nutrition of the prey's body and to fill the digestive tract of the prey with nutrients. As the term suggests, gut loading is usually looked upon as a way to get essential nutrients into a reptile via the ingestion of the digestive tract of the prey. The two methods of nutrient uptake are important due to the ability of the prey to process nutrients into a digestible form for the predator. For example, most prey can digest complex carbohydrates into other forms of nutritional energy which the predator can use. However, gut loading nutrients like calcium do not have to be digested by their prey before its death in order to be available to the predator.

Ok! Nutritious you say! Well my pangea is packed full of nutrients so I’m giving my feeders the same nutrition as my geckos when I throw my old dishes in there!

NO! You are not... As your food sits out exposed to air, light and fecal matter from your animals things happen ! Microorganisms land on the food and begin their work of breaking down the food for their own uses. The presence of oxygen enhances the growth of microorganisms, such as molds and yeasts, and contributes directly to deterioration of fats, vitamins, flavors, and colors within foods through the work of enzymes.

All food is made up of a certain percentage of water. Over time, microorganisms use the water within food to fuel the chemical reactions they need to dissolve the food for energy and growth. Moisture on the outside of food also allows molds and other microorganisms to grow on the outside of food, as well as within any cracks or holes in the surface of the food, further contributing to increased decay.

When food is exposed to light, its outer layers can begin to spoil in a process known as photodegradation. Photodegradation can result in discoloration, as well as loss of flavor, vitamins, and proteins.

Temperature also plays a role in food spoilage. As temperature increases, the chemical reactions that drive the spoiling process accelerate. That's why putting foods in the refrigerator or freezer helps to slow down the rotting process.

So in summary, not only has the food lost nutrient content but also gained microorganism content which is actually harmful. This food no longer contains the same amount of vitamins, water, and proteins it had when it was fresh. Therefor your feeders are only getting a small fraction of the nutrition the cgd once had and your gecko is getting even less than that. So what is the lesson here? Fresh Food is The best Food!

How Do I Properly Gutload? (The Following information is an Excerpt From Allans Pet Center)

"Research varies on what are the optimal gut-loading times and duration. The general consensus is that feeder insects should be allowed to gut load between 24 and 72 hours before using the feeder insect as a meal. You can determine a more specific time frame by making sure to feed the insects to your reptile before the insect can pass the waste from the gut loading meal. If you keep insects readily on hand and have to feed them a regular diet, you should have some idea of the window of time to operate within. The insect should be allowed to feed for 24 hours in total."

Remember that the primary diet of feeder insects affects their nutritional content in addition to gut loading. If you keep insects readily on hand, you will have to feed them to keep them alive, as well as feeding that final gut load. Their primary diet will also give you an idea of the foods they may avoid, so you will know not to include such foods in the gut load meal. Most insects can be fed with a commercial diet or a mixture of leafy greens and brightly colored fruits and vegetables.

Suitable green vegetables for the gut load include:

  • Collard greens

  • Kale

  • Mustard greens

  • Romaine lettuce

Brightly colored plants to gut load your feeders include:

  • Carrots

  • Oranges

  • Potatoes

  • Apples

  • Squash

  • Sweet potatoes

You can also feed the insects grain. Acceptable grains can include:

  • Baby rice cereal

  • Wheat germ

  • Alfalfa

Insects must stay hydrated, so allow them to consume fresh produce, hydration gels, or fresh water. Oranges are recommended for their ability to promote hydration in feeder insects. Insects drown easily, so ensure there are easy escape routes from a water container, and change the water regularly to prevent bacterial build-up. Insects fed a commercial, high-calcium gut load diet may stop eating fresh produce and must be provided with water for hydration. Even with all this variation, it remains possible that a gut load may be insufficient in certain vitamins or minerals. Dusting the insects with calcium and multi-vitamin powders serves to cover any final potential insufficiencies.

It should be noted that the nutritional content delivered by dusting can be difficult to measure. Some of the powder is rubbed off by the insects’ grooming before your reptile feeds. Alternatively, you can sprinkle the gut load food with the reptile multi-vitamin powders so that the powders sit in the insect’s digestive tract.

Gut load food comes under two categories: dry and wet. Wet food is anything that contains moisture and will help keep the feeder insects hydrated. Most commercial nutrient mixes are dry rather than wet. Water gels pair well with fresh vegetables to maintain good nutrition and hydration. Hydration is just as important to the health component of the feeder insect as the gut load material. Offering dehydrated prey to a reptile can wind up dehydrating your reptile. Most reptiles will need high amounts of calcium, so be sure and allow the insects to feed on high calcium options.

Examples of this include:

  • Acorn squash

  • Butternut squash

  • Sweet potatoes

  • Collard greens

  • Mustard greens

  • Kale

Avoid spinach, as it contains oxalate, which binds with calcium and makes it unable to be synthesized by your reptile. If you vary the gut load between groups of feeder insects, then your reptile will maintain a healthy and varied diet. Check with your veterinarian or research thoroughly before trying new foods for gut loading. Providing a good diet and hydration will help keep feeder insects alive until you need them as prey.

Finally, there are potential pitfalls concerning gut loading. Certain studies have shown that commercially available dry gut load diets are inconsistent with the amounts of calcium they display on the label. Therefore, dusting should be considered. They also contain particle sizes that are too large for insects to eat, defeating the purpose of the gut load. It is vital to quickly feed the insect to your pet after the insects have gut loaded before they expel the nutrients they cannot digest.

And Then There Was The Nasties...Dun Dun DUNNNNNNN

"OK, buttttt all of that doesn't sound too bad....."

Well! That's because we have yet to get to the real nitty gritty down and dirty science. Geckos....well....They...POOP!!! Shocking we know!!! Your reptile may not poop directly in their food and water dishes all of the time, but they do poop all over the place and then they walk all over the place including walking through their food and water dishes. Trace amounts of fecal matter, dirt etc can easily be transferred to the food dish. As well as any feeder insect in the enclosure can aid in the transfer of contaminants. And do you know what is in poop? Parasites! That's right! Your reptile could actually be host to parasites like pinworms OR a feeder insect you may have gotten could have been host to parasites and you unknowingly fed it to your reptile and now that infected animal spreads the eggs and parasite through fecal matter which you would in turn be feeding back to your feeders and infecting multiple other feeders which will then spread back to your reptiles. PHEW! You are also spreading back bacteria and molds to your feeders which is hazardous to their health especially if your feeders happen to be roaches! But let us discuss the different parasites and the common ways they are spread!

The 3 Most Common Reptile Parasites:

(Information as follows is taken from The Bug Shed )

Worms are the most common intestinal parasites in reptiles; that’s not to say there aren’t others to be concerned about. However, the 3 most common parasites reptile keepers encounter with their pets are:

  • Pinworm – Crickets are THE #1 source of pinworms in beardies and other reptiles. Pinworms (Oxyurids) are small nematodes (roundworms) commonly found in herbivorous, insectivorous and omnivorous reptiles. We encounter these parasites frequently in tortoises, geckos and Bearded/Rankin´s Dragons, to name a few. There are many different species (i.e. Pharyngodon sp.) and appearances found in reptile faecal samples. These parasites are found in different animal groups, including humans (human pinworm: Enterobius vermicularis) reptiles and rabbits, amongst others. Pinworms are host specific and therefore, dogs, cats and other pets do not play a role in the spread of human pinworms. Reptilian pinworms do not pose a threat to humans (not zoonotic), as in this case they are considered reptile specific.

  • Hookworm – Aptly named for what they are, hookworms have tiny hooks affixed to their head, which they use to attach themselves to the gut walls of your pet. They then siphon nutrients from your reptile, leading to illness and wasting.

  • Flagellates – Flagellates are typically found in the intestinal tract of an infected reptile. A low concentration of flagellates in a reptile is relatively common. Illness occurs when these parasites get out of control.

"Well it says pinworms are species specific...So my geckos won't get pinworms so that's fine...."

Yes, pinworms are specifies specific however there is a catch. It is presumed that insects may ingest the eggs and when the reptile consumes the insect, these can be passed on to the reptile. Insect pinworm eggs may be found in reptile feces (i.e a reptile ingests a cricket). These would be classified as reptile pseudoparasites, meaning that they would simply "transit" or "pass through" the digestive tract (as they are pinworm eggs of insects). The reptile then sheds some parasites in its feces, the feeders then eat the feces, thereby taking on a bigger parasite load, your reptile then eats these crickets, and so the cycle goes on). And Vice Versa which is why you NEVER want to put an uneaten feeders back into your feeder colony. (excerpt from Parasite Vet UK)

So now that you know Reptiles can harbor and assortment of parasites and worms which can also be passed to your feeder colonies through....You guessed it? Those dirty dried food dishes...We can Move onto Mold, fungi And Bacteria!!!

My Dubia Are A Clean Up Crew!!

No, they are not...Mold and Bacteria can actually be harmful to your dubia. They can cause sickness and die offs potentially wiping out your colony.

Mold & Fungus For they are Among Us:

Dubia roaches naturally live on the forest floor, and this is a mold and fungus-rich environment. However, molds and other fungi have been known to wipe out captive colonies, so the lesson seems to be something like this: Keeping Dubia roach colonies in dark, wet, hot boxes is different than living free in the rain forest. The fruits and diets we feed to our reptiles produce molds of the Aspergillus or Penicillium species. These molds produce toxins that are deadly to roaches and can kill of entire colonies and can even make your reptiles potentially sick if the roaches eat too much of it.


As mentioned above, Dubia roach enclosures are a prime environment for bacteria. The good news is that most bacteria are harmless. Some are even beneficial. For example, Dubia roaches require that a certain bacteria colonize their gut to help them digest food. And, certain micro-organisms may provide them with key macronutrients when they are lacking in the diet. But there are bad bacteria too, and if one of these bad bacteria makes its way into your colony, it can take hold and make it sick. It could even wipe it out. The key variable here is the environment, and of course, what you put in it. You can control both things within reason. Dubia roaches need humidity to breed. They also need heat, but their enclosure doesn’t have to resemble a sauna.


The simple act of feeding Dubia roaches introduces all sorts of foreign matter from any number of places into the environment that was just described above as prime for the spread of bacteria. Have you ever been to a farm or seen the back of a delivery truck? These are not clean places. Bacteria are everywhere. One spot of dirt on one piece of vegetation can harbor millions of germs…all waiting to find a new home in a dark, wet, hot place just like your Dubia roach colony. (information from

So what does that mean?

well that means that those things on their own are dangerous to your feeders. By adding your old gecko food to the equation that can contain harmful molds and bacterias you are introducing those potentially dangerous factors directly into your feeder colonies. It is not healthy or a safe practice. “well nothing has happened to my geckos. So it’s fine.” Nothing that you know or visible or maybe it hasn’t. However, they are not receiving the absolute most health wise out of their insects which is the whole point of feeding insects. And how well are your feeders thriving? If they are thriving at all...So in order for your feeders and geckos to benefit you should only be feeding healthy fresh fruits, veggies or diets.

"Ok....But then what do i do with all this left over food my gecko doesn't eat? I don't want to throw it away it's a waste..."

Tips To help with Food Waste

  • If you notice your gecko is not eating an entire 1oz or 2oz cup of food feed only the amount of food that you notice they eat. if they leave half a cup only offer half a cup. Crested Geckos do not have big stomachs so therefore don't need to be fed large quantities of food in one sitting.

  • Do you spray your geckos enclosures at the same time you are feeding? If so, this could be contributing to why the are eating less until. they are filling up on water prior to eating. Spray your enclosures early that day or two hours after offering food.

  • "My geckos only eat food the next day cause it's mimicking rotting food..." No, it's probably not... This can happen for a couple reasons like they were full from water their food was too watery when offered. Geckos can be very picky about their food consistency and wont eat food that is too watery or too thick, but they will eventually eat it because they have no other option.

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