Choosing the Best Insects and Gut Loading Properly
Options for feeding insects vary from reptile to reptile based mainly on size constraints. For example, poison dart frogs can really only be fed fruit flies and sometimes tiny crickets. However, other animals can eat a wide variety of feeder insect species. With a combination of proper gut loading and feeder choice a healthy diet can be made for any insectivore. Dusting is another option, but in most cases does not provide enough of a supplement to account for the deficiencies in insects.
Common Nutrient Deficiencies
Unfortunately, as of this writing only five species of feeder insect have had a complete nutrient analysis conducted. From this analysis it can be seen that almost all feeder insects are deficient in calcium and vitamin E. Many are also deficient in vitamin A. Because of this data, it should be assumed that all feeder insects are deficient in these nutrients until proven otherwise.
Calcium Rich Feeders
Many different feeder insect are often claimed to be "calcium rich," but really only one species of commercially available feeder insect has a higher that 1% calcium content by dry matter. This is the minimum amount of calcium needed by reptiles so it should be the cutoff for considering a feeder insect "calcium rich." This insect is the black soldier fly larva. It is often sold as "calciworms," "reptiworms" or "pheonixworms." It is truly the best feeder insect. It has (on a dry matter basis) 50.5% protein, 22.2% fat, 3.02% calcium and 0.93% phosphorus. This insect is not too fatty while having tons of calcium. Note that vitamin A and E still need to be gut loaded into calciworms.
Typical Feeder Insects
Typical feeder insects are low in calcium and are not too high in fat content. Vitamin A is variable due to the fact that this is highly dependent on the diet of the insect. No matter what species of insect you choose it is critical to gut load with vitamin A. This category of insects is great for adult animals that do not need excess calories. They include crickets, silkworms, earthworms, fruit flies, dubia roaches, hornworms and butterworms. Some of these species have very little information about their nutritional content beyond that they are moderate in protein, low to moderate in fat and low in calcium. Unless the nutrition information is listed below assume that they need extensive vitamin and mineral supplementation.
Fatty Feeder Insects
These insects make a good treat for healthy adult animals. They also are good for growing or underweight reptiles. They all consist of over 25% fat on a dry matter basis. They include superworms, mealworms, waxworms, and american cockroaches. Remember that like typical feeder insects these insects need to be gut loaded to increase their calcium, vitamin A and other nutritional value.
Nutrient Content of Un-Gut Loaded Insects
Why This Is
Looking at a comparison of insects against the requirements of reptiles allows the benefits and
disadvantages of each insect to be weighed. It also allows for correct supplementation to overcome
any nutritional shortcomings. Remember to always gut load insects to increase their nutritional content.
Finke, Mark D. Complete Nutrient Composition of Commercially Raised Invertebrates Used as Food
for Insectivores. Zoo Biology 21:269-285 (2002)
Nijboer, Joeke. Ed. Nutrition in Reptiles. Merck Veterinary Manual. 2015
Bernard, Joni B. and Mary E. Allen. Feeding Captive Insectivorous Animals: Nutritional Aspects of Insects as Food. Nutrition Advisory Group Handbook. 003 (1997)