Updated November 5, 2020
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How often do you check the nutrition facts on the food you eat? Depending on your fitness and dietary goals, you probably pay attention to carbs, fat, protein, and vitamins. Paying attention to what you eat and pursuing a balanced diet is part of staying healthy as a human. Similarly, paying attention to what you feed your reptiles is key to keeping them healthy.
Both insectivorous and omnivorous reptile species need to eat bugs as part of a balanced diet. But just like fruits and vegetables have different levels of nutrition, so do different kinds of feeder insects. Knowing the nutrient ratios of the insects you give to your reptiles can help you provide more precise nutrition for your reptiles’ individual needs.
The nutrients that you want to pay attention to are Protein, Fat, Fiber, and Ash.
Protein is essential for building and maintaining muscles, as well as assisting proper organ function and providing energy. High protein insects are great for helping sick or injured reptiles recover, as protein is used for cell maintenance and repair.
It is advised that strict insectivores (reptiles that only eat bugs, no veggies) must be fed a variety of insects to make sure they get the nutrients they need, as some feeders are higher in nutrients than others. Varying gut loads can also help in this respect.
Fats in insects are generally unsaturated, while birds and mammals (what humans eat) tend to be saturated. However, a high fat diet is still unhealthy for reptiles. The fats may be “healthy” by our considerations, but fat as a nutrient is very high in energy: 9 (kilo)calories per gram of fat, versus 4 (kilo)calories per gram of protein or carbohydrate.
Excess energy gets converted to fat, which can contribute to obesity in pet reptiles. Obesity is common in this setting, as captive reptiles typically get less exercise and more food than in nature. Furthermore, overzealous keepers who like to “spoil” their pets with treats and extra food can also drive them to obesity.
That being said, a no-fat diet isn’t the solution either. It doesn’t work for humans and it doesn’t work with reptiles. Fats are essential for a variety of functions:
- Assists absorption of certain vitamins (vitamins A, D, E, K)
- Cushions internal organs
- Helps create fat stores for brumation and egg laying
- Helps maintain body temperature
The Merck Veterinary Manual recommends that linoleic acid (Omega 6 fatty acid) be included in the diet for overall health. All insects except roaches contain linoleic and linolenic acids, so variety is beneficial.
Fiber in insects comes mostly from chitin, or the insect’s exoskeleton. So basically, it’s a complex carbohydrate — the good stuff. The amount of fiber in an insect is typically very low; high amounts can lead to digestive issues if fed too often or in excess. Insectivores are better able to digest high levels of chitin than frugivores/herbivores or even omnivores, as their bodies are built to handle it.
Just in case you get any ideas, the hardness of an insect’s exoskeleton does not indicate higher fiber levels (or chitin content). Instead, it’s due to certain protein chains used to reinforce the exoskeleton.
What the heck is ash? It’s the leftovers — the parts of the bug that aren’t protein, fat, or fiber. This is typically composed of salts, minerals, and metals, including the insect’s gut contents. Higher levels of ash, then, can be assumed to correlate with higher levels of vitamins/minerals as well as a larger gut capacity.
Ca:P — The Calcium to Phosphorus Ratio
You’ve probably seen this mentioned in the context of supplements — if you’ve read my article, What You Need to Know About Reptile Vitamins, it’s probably especially familiar. That’s because like UVB and vitamin D3, knowing how to balance your reptile’s dietary calcium and phosphorus intake is critical to managing its health.
Reptiles require twice as much dietary calcium as they do phosphorus. This is because in order to properly metabolize (or digest) phosphorus, calcium must be present. In other words, they require a dietary calcium to phosphorus ratio of approximately 2:1. When there isn’t enough calcium for the reptile’s body to properly process phosphorus, it will steal calcium from bones and other stores. Over time, this repeated robbery of calcium can lead to MBD.
Most insects contain more phosphorus than they do calcium, which is why we dust (a common exception is black soldier fly larvae, and we’ll get to that in a bit). Calcium supplements are designed to correct the natural imbalance between calcium and phosphorus. When choosing a calcium powder, make sure that it does not contain phosphorus or more than 5000 IU/kg of vitamin D3.
- Repashy Supercal
If you have a calcium deficient reptile, Repashy RescueCal+ is a good choice to help them recover.
“Dry Matter” vs “As Fed”
Most insect nutrition is measured in “Dry Matter,” or nutrition of an insect based on its nutritional value when dried out. Moisture content (“As Fed”) can distort individual nutrition percentages. However, when comparing nutrient value between feeder insects, the opposite holds true: As Fed is more accurate.
Fortunately, if you know the moisture percentage of a feeder, you can convert from As Fed to Dry Matter basis and vice versa with a little basic math.
Converting from As Fed to Dry Matter: Divide percentage of nutrient As Fed by the percentage Dry Matter, and then you get the percentage of nutrient by dry weight.
Converting from Dry Matter to As Fed: Multiply the percentage of Dry Matter by percentage of nutrient.
Why should you care? Knowing these percentages gives you the knowledge to make educated decisions about which feeders to give your reptiles, and how often, based on individual needs.
ReptiFiles’ Chart of Feeder Insect Nutrition Facts
By this point you’re probably wondering how accurate this information can be. Of course, the specific nutritional value of any given feeder insect will vary depending on the quality of its gutload and the breeder’s insect husbandry. This data assumes that each feeder is properly gutloaded and healthy, and has been averaged from the sources of nutritional information that I’ve found for each type.
The following data is presented “As Fed,” and has been rounded to the nearest percent for simplicity’s sake.
nd = No data
|Black soldier fly larvae||64%||17%||11%||6%||5%||variable||Also known as Phoenix worms, NutriGrubs, or calcium worms.|
|Butterworms||60%||16%||17%||1%||1%||1:18||High fat and phosphorus; treat only. Butterworms secrete an acid-like substance that can burn gecko skin.|
|Crickets||73%||18%||6%||2%||2%||1:9||(Acheta domesticus) High calcium crickets have a 1:1 Ca:P, and pinheads are 1:6|
|Death’s Head roaches||79%||11%||nd%||nd%||0%||nd|
|Earthworms||82%||11%||3%||2%||1%||1.5:1||Do not buy worms raised for bait.|
|Fruit flies||70%||21%||5%||5%||2%||1:10||(Drosophila melanogaster)|
|Grasshoppers||72%||20%||2%||5%||2%||nd||(Phymateus saxosus) Farm-raised only. Wild individuals are likely to be toxic due to milkweed diet.|
|Giant mealworms||nd||17%||21%||nd||nd||1:3.5||High fat; treat only. Not the same as superworms.|
|Giant Mealworms (high calcium)||nd||15%||17%||nd||nd||1:1||High fat; treat only. Not the same as superworms.|
|Nightcrawlers||84%||10%||2%||2%||2%||1.5:1||Do not buy nightcrawlers raised for fishing bait.|
|Red Runner roaches||71%||18%||6%||2%||2%||nd||(Blatta lateralis) Also known as the Turkestan cockroach or Rusty Red roaches.|
|Silkworms||79%||13%||2%||3%||1%||1:2.4||Silkworms fed artificial diet are significantly more nutritious than those raised on mulberry leaves only Data is averaged between the two.|
|Snails (without shell)||76%||19%||1%||3%||2%||nd||Based on garden snail, Achatina fulica. No data available on nutrient value of snails with shells, but shell presence is known to correct calcium imbalance.|
|Superworms/Morio worms||60%||19%||16%||4%||1%||1:18||High in fat and phosphorus; treat only.|
|Wax worms||62%||14%||18%||3%||1%||1:7||High fat; treat only.|
How to Create More Variety in Your Reptile’s Diet
As mentioned previously, variety is the key to optimum health in a reptile’s diet. You don’t think that wild reptiles only eat one or two types of foods, do you? If they were that picky, they would have died out due to starvation long ago. This variety in their diet provides a wild spectrum of nutrients and creates a foundation for optimal health.
Of course, offering a variety of insects is more difficult for a pet reptile than it is for a wild reptile. There’s a huge variety of bugs ready-to-eat in the wild. For captivity, they need to be intentionally raised or purchased one by one. Here are some methods that I’ve personally found effective for increasing variety in my insectivorous and omnivorous reptiles’ diets:
Buy your bugs online. It’s more convenient to buy feeder insects from your local pet store, but pet stores often have a very limited supply of available feeders — if you’re lucky, you might have access to crickets, mealworms, dubia roaches, hornworms, superworms, and waxworms. But if you head online, you’ll be able to find a wider variety of feeders to try with your reptile. Here are some of my favorite outlets for purchasing feeder insects:
Try canned insects. They may seem gross, and they definitely don’t smell like roses. But canned bugs are available at most pet stores, and are tasty enough to be readily accepted by most reptiles. What I like best about them is that they give me access to certain types of feeders that are hard to find anywhere else, such as snails (shell-less, unfortunately) and grasshoppers. Zoo Med is my go-to for canned bugs, but Exo Terra, ProBugs, and Dubia Roaches are also good.
Go foraging. Collecting wild insects is a faux pas in many Facebook reptile groups, but the fact of the matter is that it’s only dangerous if you accidentally collect something poisonous or collect them from a polluted area. This can be easily prevented by only collecting from areas untainted by pesticides, herbicides, or vehicle exhaust, and identifying the bugs you’ve collected before feeding them to your reptile. Many people are concerned about the danger of parasites with this practice, but in truth, wild insects are likely to have lower parasite loads than captive insects because they are generally healthier.
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