Somewhere between picking up your first gecko and picking up your fifth, you run into a feeder nutrition chart. It has a lot of decimal places and no explanation. This guide covers what those figures actually measure, why two charts of the same insect disagree by a factor of three, and which of the numbers should change anything about how you feed.
The six numbers on almost every feeder analysis
Laboratory analyses of feeder insects nearly always report the same short list. Everything else on a chart is derived from these.
- Moisture. How much of the insect is water. Feeder insects run from roughly 55% to 85% water, and this single figure drives every other percentage on the sheet.
- Crude protein. Measured as nitrogen and multiplied by a conversion factor. In insects that factor is contested, because some of the nitrogen sits in chitin rather than in protein, which inflates the result.
- Crude fat. Usually reported as ether extract. This is the figure that varies most between species and the one that varies most with what the insect was reared on.
- Ash. What is left after the sample is burned. It stands in for total mineral content, and in most feeders it is low.
- Fiber, as ADF or NDF. Acid or neutral detergent fiber. In insects this is mostly cuticle, and it gets read as a proxy for chitin, which is only roughly true.
- Calcium and phosphorus. Reported separately and then as a ratio. For anything with a skeleton, this is the pair that matters.
Check the basis before you compare anything
The same insect produces two entirely different-looking sets of numbers depending on whether the water is counted.
As fed, sometimes called wet weight, includes the insect's moisture. Dry matter, written % DM, has the water taken out. A house cricket is around 28% dry matter, so a protein figure of 63% DM and a protein figure of 18% as fed can describe the same cricket. Neither is wrong. Comparing one to the other is.
Most of the reptile-keeping charts circulating online are as-fed. Most of the insects-as-feed research literature is dry matter. A surprising number of charts do not say which, and a few appear to mix both in one table. If a chart does not state its basis, treat the whole thing as unverified.
What published analyses generally show
The table below is drawn from published feed-composition databases that aggregate peer-reviewed analyses, so every figure is a range across multiple studies rather than a single measurement. It is on a dry matter basis throughout. These are not our figures and we have not run our own analysis on anything.
| Feeder | Dry matter (% as fed) | Crude protein (% DM) | Fat (% DM) | Calcium (g/kg DM) | Phosphorus (g/kg DM) |
|---|---|---|---|---|---|
| House cricket | 23 to 33 | 55 to 67 | 10 to 23 | 2.1 to 13.2 | 7.8 to 7.9 |
| Mealworm larva | 31 to 58 | 47 to 60 | 26 to 43 | 0.3 to 6.2 | 4.4 to 14.2 |
| Black soldier fly larva | 35 to 45 | 22 to 66 | 29 to 52 | 1.2 to 35.7 | 1.0 to 10.3 |
Read the width of those ranges, not their midpoints. The black soldier fly row spans a threefold difference in protein and a thirtyfold difference in calcium. That is not sloppy measurement. It is a real property of an insect whose composition tracks whatever it was raised on.
Published analyses of the other common feeders land in familiar places. Waxworms and butterworms come out high in fat and low in protein relative to their weight. Silkworms come out very high in moisture and correspondingly low in everything else. Roach nymphs sit close to crickets on protein with somewhat more fat. Superworms sit close to mealworms. None of those species has enough independent published analyses behind it for us to put a defensible range in a table, which is why they are described in words here instead of tabulated. Our bearded dragon feeder guide has an as-fed table with single published figures for most of them, side by side.
Why the same insect gets two different numbers
Whether it was fasted
This is the biggest single reason for disagreement, and it is rarely made obvious. Some studies fast the insects for 24 hours before analysis, so they are measuring the insect. Others deliberately do not, so they are measuring the insect plus whatever is in its gut, which is what your animal actually eats. Researchers comparing cricket calcium values across studies have pointed directly at this as the likely explanation for results that differ several-fold. Both approaches are defensible. They answer different questions.
What the insect was reared on
Black soldier fly larvae are the extreme case, and reviews of the species are explicit that fat and ash content shift substantially with the rearing substrate. It applies more quietly everywhere else too. A mealworm raised on bran alone and a mealworm raised on bran plus vegetables are not the same feeder.
Life stage
Nymphs, larvae and adults of the same species differ. Cricket nymphs carry more water and less fat than adults. A freshly moulted insect of any species has a softer, thinner cuticle than one about to moult, which changes both the fiber figure and how much of it your animal can actually get at.
How the lab measured it
Fiber is the clearest example. Using acid detergent fiber as a stand-in for chitin overestimates it, because the ADF fraction in insects contains amino acids that are not chitin. Work correcting for this found meaningfully lower chitin figures than the raw fiber numbers suggest. If two charts disagree on fiber, the method is often the reason.
Which numbers should change what you do
Most of a nutrition chart is context. A short list of it is actionable.
- Calcium to phosphorus is the one to act on. Almost every commercially raised feeder has more phosphorus than calcium, which is the wrong way round for a growing reptile. This is what dusting and gut loading exist to fix. Start with the Ca:P guide.
- Fat is worth acting on for the high-fat feeders, which are treats rather than staples for most species. See protein, fat and moisture.
- Moisture matters if you keep something that drinks poorly, and it also means a gram of silkworm and a gram of superworm are not comparable amounts of food.
- Fiber and chitin matter less than the internet suggests, and mostly at the margins. See chitin and digestibility.
What a nutrition chart cannot tell you
A composition table tells you what is in the insect. It does not tell you how much of that your animal absorbs, and those are different numbers. A feeding trial in leopard geckos found dry matter digestibility of intact black soldier fly larvae around 71%, but calcium digestibility only around 43%. An insect that looks calcium-rich on paper can deliver much less than the paper implies.
A chart also cannot tell you anything about the animal in front of you. Species, age, whether it is growing or gravid, lighting, and whether it basks all change what the same insect is worth. Nothing here is veterinary advice. If an animal is showing signs of a nutritional problem, that is a conversation with an exotics vet, not with a spreadsheet.
Where to start
If you are picking a staple, the practical order is: choose a feeder your animal will reliably eat, size it correctly, then fix its mineral profile with gut loading and dusting rather than hunting for a feeder that does not need fixing. Very few of them exist.
We sell dubia roaches and the common larval feeders, all on our feeders page; we do not sell crickets. Our leopard gecko feeder guide lists the feeders commonly used for that species. Next, read how to gut load feeder insects and dusting feeders with calcium and vitamins, which are the two things that actually change the numbers. If your feeders have just arrived, what to do when your feeders arrive covers settling them in before you start loading them.