Up until recently there was little detailed nutritional information about commercially raised insects. However in the last 10 years the nutrient content of the most common commercially raised insects has been published in peer reviewed journals. These analyses include house crickets (Acheta domesticus), waxworms (Galleria mellonella larvae) mealworms (Tenebrio molitor larvae), superworms (Zophobas morio larvae), silkworms (Bombyx mori larvae) butterworms (Chilecomadia moorei larvae), soldier fly larvae (Hermetia illucens larvae) and several species of roaches and locusts. Some of these data are summarized in table 1. While the food the insect consumes as it grows can modify the nutrient content of the insect, these data provide sufficient information to suggest some general guidelines regarding insect nutrient content. These data also provide the background from which to develop appropriate gut-loading diets or dusts which can enhance the levels of nutrients that are low in commercially raised insects.
Pet owners should be careful when using insect nutrient data found online. Much of it reviewed by this author was found to be inaccurate. While the exact reasons are unclear, it may be that the website did not properly report previously published peer reviewed data, they had their insects analyzed by a commercial laboratory that was not capable of accurately analyzing live insects or in some cases they simply copied inaccurate data published elsewhere online. The reader should always ask where the nutritional information found online comes from. Peer reviewed published research articles are the best source of reliable information although some good unpublished information is available. When in doubt call or e-mail the website and ask them the source of the information.
* – Fiber measured as acid detergent fiber.
Summary of the Major Nutritional Components
The five major nutritional components of live insects are moisture, protein, fat, fiber and ash generally in that order; however some species of insect larvae contain more fat than protein (see table 1). While statements like “some insects are too hard” or they “contain too much chitin” or they “have too much shell” and thus are inappropriate for some species of insectivores are commonly encountered online, those statements have little basis in fact. Most insects contain relatively small amounts of chitin (chitin is only present in the cuticle/outside layer of the insect) and it is unlikely to be an issue for insectivores eating a diet consisting of multiple species of appropriately sized commercially raised insects.
In general insects contain very little calcium and have a calcium:phosphorus ratio of less than one. A small number of insect species have a mineralized exoskeleton and hence contain significant amounts of calcium including black soldier fly larvae, a species which is commercially available (sold as Calciworms®, Phoenix worms® or Reptiworms™). As such soldier fly larvae can serve as a good source of calcium for insectivorous lizards (when feeding other species of insects calcium can be supplied by either dusting or by gut-loading). When properly done with the right products both gut-loading and dusting can be effective. Crickets and some other insect species will rapidly groom off adhering dusts so the insect must be consumed quickly. Properly formulated gut-loading diets have been shown to increase the calcium content of house crickets, wax worms, mealworms and silkworms from 5-20 fold. It should be noted however that many commercially available gut-loading diets failed to increase the calcium content of crickets presumably due to improper formulation. Other than calcium most insects appear to be good sources of most minerals. These include the macro-minerals phosphorus, magnesium, sodium, potassium and chloride and the trace minerals iron, zinc, copper, manganese and selenium.
Insects and Vitamins
There is only limited data available on the fat-soluble vitamin content of insects. To date, all commercially bred insects analyzed contain virtually no vitamin A, very low levels of vitamin D and vitamin E levels that are much lower than those found in wild-caught insects. Vitamin A deficiency has been reported in a number of species of captive insectivorous lizards and amphibians fed commercially raised insects. Additionally most commercially raised insects contain almost no carotenoids while most wild caught insects contain a number of different carotenoids including β-carotene, lutein and zeaxanthin. Some species of vertebrates can convert some of these carotenoids to vitamin A and so in the wild they may serve as a source of vitamin A for insectivores although nothing is currently known regarding the ability of insectivorous lizards to convert carotenoids to vitamin A. Feeding carotenoids to several species of amphibians has been also shown to enhance both reproduction and animal coloration so carotenoids may play other important roles for insectivores. Recently crickets, mealworm, superworms and waxworms with enhanced levels of carotenoids, vitamin E and omega-3 fatty acids have been introduced to the market (Vita-bugs®; Timberline Live Pet Foods, Marion, IL).
In contrast to the data for fat-soluble vitamins, all insects analyzed to date appear to be excellent sources of most of the water soluble/B-vitamins. The only exception is thiamin (vitamin B1) where many species appear to contain relatively low levels. It is important to note that thiamin deficiency has recently been reported in a colony of Puerto Rican Crested Toads fed exclusively crickets.
In summary, insects are rich in many nutrients especially protein/amino acids, most minerals (except calcium) and most B-vitamins. Nutrients which are low in most commercial insects and for which deficiencies have been observed in captive insectivores include calcium, vitamin A and thiamin. While deficiencies have not been reported, other nutrients of possible concern based on nutrient analysis of insect include vitamins D and E, omega-3 fatty acids and carotenoids. While our knowledge of insectivore nutrition is very limited, feeding insectivores a diet composed of a variety of different species of commercially raised insects is likely the best way to reduce the risk of nutritional deficiencies. Particular attention should be paid to the intake of calcium, vitamins A and E, carotenoids and thiamin either through feeding a diet of mixed insect species and/or through the proper use of gut-loading or dusting. The exact mix of insects may vary depending on the situation. For example overweight animals may benefit from a lower fat diet (fewer mealworms, superworms, waxworms and butterworms) while sick underweight animals of the same species may benefit from a diet with more high fat/high calorie larvae.
Finke MD. 2002. Complete nutrient composition of commercially raised invertebrates used as food for insectivores. Zoo Biology 21:286-293.
Finke MD. 2003. Gut loading to enhance the nutrient content of insects as food for reptiles: A mathematical approach. Zoo Biology 22: 147-162.
Finke MD, Dunham SD, and Kwabi CA. 2005. Evaluation of four dry commercial gut loading products for improving the calcium content of crickets, Acheta domesticus. Journal of Herpetological Medicine and Surgery 15: 7-12.
Finke MD. 2013. Complete nutrient content of four species of feeder insects. Zoo Biology 32:27-36.
Oonincx DGAB and Dierenfeld E. 2011. An investigation into the chemical composition of alternative invertebrate prey. Zoo Biology 29:1-15.