This guide contains in-depth nutrition and husbandry information for 20 of the most common feeder insects for reptiles, amphibians, and arachnids. It is essentially divided into two main sections: Insect nutrition data and head-to-head comparisons.
- The insect nutrition data
- The head-to-head comparisons
- Sources and references
The “data” section is a compilation of key nutritional information for each of the 20 insects. We got this data by doing what amounts to a meta analysis of academic, industry, and other studies on insect nutrition. We pulled all the relevant studies we could find, analyzed the data, crunched the numbers…and then we organized the results in sortable tables to make it easy to compare and contrast.
The final results come from pooled, normalized data that we boiled down to something meaningful so herp owners can use it to make real-world decisions about what to feed their animals. Do you want to know which bug has the most calcium or the highest Ca:P ratio? No problem. Just sort the data by your metric of choice to see how the insects compare.
The “head-to-head” comparisons addresses insect husbandry and goes beyond nutrition data – though it may include it. In this section we directly compare insects to give you a sense of what it’s like to feed, keep, and breed each of them. We do this by comparing each insect in a head-to-head match-up with the Dubia roach. Essentially, we use B. dubia as a benchmark. This allows contrasts to be drawn not just between each insect species and the Dubia roach, but indirectly between each insect.
While each match-up touches on nutrition, the goal is to provide a realistic idea of what you will be dealing with after you get each insect home. Did you ever try breeding crickets only to find that they smell horrible after a few weeks? Our head-to-head comparisons address these types of issues and more.
The goal of all this, in short, is to provide information in a way that helps you choose the best feeder insects for both you and your animals, given your unique situation.
Feeder insect nutrition and husbandry
Practically speaking, these two things are inseparable. It makes little sense to buy a super nutritious insect if you are unable to house it, and there is not much to gain by feeding your animals insects that are easy to keep and breed but have little nutritional value.
This guide was conceived as a way to spare readers the hassle of trial and error by bridging the knowledge gap between insect nutrition and husbandry. Each feeder has its own unique nutritional profile and personality. Every animal has specific nutritional needs. And, each pet owner has a set of circumstances that they operate within. The closer the fit between these three things the better the user experience will be.
Nutrition is among the top concerns for both amateur and professional herp caretakers. Unfortunately, nutritional deficiencies are common in captive reptiles, amphibians, and arachnids.
As you may know, diets chronically deficient in certain nutrients can lead to serious and sometimes irreversible health problems. For example, calcium deficiency can lead to Metabolic Bone Disease. Hypovitaminosis-A can develop in response to too little vitamin A. And the list goes on. All animals need a reliably nutritionally adequate diet, and this can be tough to provide in captivity. Nutrition is important at all life stages, but it is especially important for animals that are growing or reproducing.
In the wild, dietary diversity solves this problem even though sometimes volume is lacking. In captivity, lack of food is rarely a concern, but lack of diversity is.
For these reasons it is important to get herp nutrition right. This is why we compiled data not just for a few, but for 20 of the most commonly available feeders on the market. You can buy most of the 20 insects online or at local pet stores, and we even threw in a few local insects that may live in your area. If this article inspires you to do a little hunting, you just may find one or two of the native species in your own backyard.
In the course of compiling the data we decided to take the next step and do individual head-to-head comparisons between each of the 20 feeders and the Dubia roach. In addition to providing the information you need to make informed dietary choices for your animals, we can help you do it in a way that meets your needs too.
As you may know, feeder insects are not without husbandry concerns. Issues relating to smell, noise, diet, and cleanliness are a reality that you should be aware of before making decisions, not after. Certain bugs can be aggravating, and to some people in certain situations more than others. What works for one may not work for another. Our in-depth husbandry comparisons are detailed by design in order to give you a sense of which insects may work for you and which ones may not before you make a purchase.
Lack of information
For such basic and useful information, we are surprised by how scarce it is. When we first got into Dubia roaches we searched online for anything that might help us understand more about insect and herp nutrition. However, most of the information we found was incomplete and unreliable. Much of it was contradictory. Most of it didn’t seem credible because it was not sourced and seemed suspiciously self-serving. Claims were often repeated by numerous websites and their basis was not only unknown or lost, but it seemed questionable that it ever existed in the first place.
For this article, we weren’t interested in hype. In fact, we wanted the opposite. The goal was to create reliable data from basic research that we could use to help make decisions. We wanted something that would be easy to understand from which “apples-to-apples” comparisons between Dubia roaches and other feeders could be made. In the end we had to create that ourselves.
Explaining data differences
It is worth noting that nutrition information for the same insect species often differs between sources. On occasion, it may differ a lot. There may be several reasons for this. Age, sex, diet, life stage, reproductive status, and environment all contribute to an insect’s nutritional status.
When we found differences in the data we tried to understand the cause. Occasionally we got lucky and something like statistical insignificance due to small sample size accounted for outliers in the data. Other times we were able to discount data because the methods researchers used was questionable.
However, there were occasions where we could not discount data and significant differences among studies could not be explained. In these cases we did our best to weigh the outlying data and include it with the rest.
That said, our results are not scientific, but we think they are pretty good. They’re certainly good enough to serve as the basis for decisions we make for our animals.
Acknowledging our bias
Finally, before we get to the data, we want to acknowledge our bias. We sell Dubia roaches. That should be clear. We think they are the most nutritious and user-friendly feeder on the market. This is why we began feeding them to our animals and breeding them.
We think the best advertising is the Dubia roach itself. Its quality is evident in the data and in our personal experience with it, so throughout our website we provide visitors with the same information that helped us form our initial opinions about this remarkably nutritious insect. Of course we hope you agree, but every situation is unique. Ultimately we want you to make the best choices for yourself and your animals.
The insect nutrition data
NOTE: All data is sortable by column. click 1: sort ascending, click 2: sort descending, click 3: reset
|Insect||Cal:P||Water%||Dry Matter%||Chitin%||Protein||Fat||Minerals (ash)|
|Black Soldier Fly Larvae
|Black Soldier Fly Larvae
As an aside, the nutrition information above can be of more practical use when you know the dietary needs of reptiles, amphibians, and arachnids. It is no surprise that carnivorous insectivores eat a wide variety of insects in the wild. A sufficiently varied diet provides all the vitamins and minerals they need. In addition to micro-nutrients, their natural diet also provides:
30% to 60% protein, 40% to 70% fat, and negligible carbohydrates according to McWilliams, 2008, and 30% to 50% protein and 50% to 70% fat according to Merck Veterinary Manuals (external link).
It seems reasonable to keep this information in mind when deciding what and how to feed insectivores. Because so few insects fall outside these admittedly wide ranges, perhaps the best way to view them is as general dietary guidelines. Maybe something to experiment with in the search for the ideal diet for your animals.
Head-to-head: The husbandry comparisons
This section provides a sense of what it’s like to keep, feed, and breed the following feeder insects compared to Dubia roaches. Since much of the experience of keeping a particular feeder is subjective, these comparisons are relative by design. We think that’s the best way to analyze and convey this information. It is difficult to quantify a characteristic like smell, for example, but it’s not so difficult to compare and contrast the smells produced by two different insects. This is something most people can understand – particularly those who have experience raising or feeding some of these insects.
While the previous section focused on data, this section explores contrasts. What distinguishes each of the feeder insects from B. dubia? Where are they similar and when do they differ? Are there any similarities at all or is the relationship defined by differences? This section is about personalities, but not just that…it’s about relative personalities. Nutritional comparisons are made here but we try to keep them brief because they are largely incidental to what we’re trying to convey, and details can be found within the tables above.
The Dubia roach vs…
The American Cockroach
Periplaneta americana and Blaptica dubia are a lot alike. That makes sense. They’re both cockroaches from the same Order. They have similar body composition. They grow to about the same size (though B. dubia is slightly bigger), and there are even similarities in the macronutrients, vitamins, and minerals they provide as feeders. However, their similarities are related almost exclusively to nutrition, not husbandry. In this regard they are two very different insects.
To start, the American cockroach is a pest. While some climates and regions are more suitable than others, only a very few are inhospitable and safe from potential infestation. And they are very fast. In fact, they are not only one of the fastest cockroach species, but one of the fastest land insects in the world (external link). If you’re worried about infestation, consider steering clear of the super-fast land speed world-record holder. And unlike the Dubia, they can fly. Both male and females are able to fly in favorable environmental conditions.
For those who decide to keep Periplaneta americana as feeders, the only other notable differences between the two are odor and longevity. American cockroaches give off an odor that’s stronger and more pungent than their Dubia counterparts. The smell is not horrible, but it is noticeable whereas Dubia enclosures tend to mostly smell of whatever food they’ve eaten, plus a slightly musky scent they give off when disturbed. In the grand scheme of things, neither smell is bad. When compared to other feeder insects, one could even make an argument that the smells are “good”. More on that later…
Regarding longevity, Dubia roach females tend to live about two years while their American cockroach peers tend to last only 18 months.
And finally, since some herp owners like self-caught insects – a word of caution. In the absence of abundance, cockroaches will eat almost anything. This includes things that are not good for animals. We don’t recommend catching your own roaches unless you’re sure they have no contact with harmful substances. However, if you do, don’t feed them off right away. Provide food, water, and shelter, and give them time to flush out their systems. Roaches have longer digestive tracts than many other insects, and what they eat stays around longer. Keep that in mind.
The Banded Cricket
Gryllus assimilis, aka the Jamaican Field Cricket or sometimes simply “field cricket”, is the cricket that took over for the Domestic House Cricket (Achetus domesticus) in the United States feeder market after the global feeder cricket pandemic of 2011. It seems these buggers have immunity to the highly contagious cricket virus that wiped out most of the U.S. stock at that time, so they got the job, and here we are. You can still buy Domestic House Crickets, but the market is comprised of mostly Gryllus assimilis.
Crickets are ubiquitous in the pet trade. We dare say they’ve gone totally mainstream. These days they’re even sold at big-box pet stores like Petco (external link). It wasn’t always this way.
As we figure it, the mainstream appeal and availability of crickets must at least in part be due to the fact that they work for retailers logistically, because nutritionally they’re just OK. Compared to other insects one might consider feasible to sell on a large scale, crickets are fairly good. They have a fair amount of protein on a dry weight basis, though a high water content means a lot less protein on a per-cricket basis. This reality of the Banded cricket’s nutrition density may explain the common experience herp owners have where animals that fill up on say a dozen crickets per day only need one good size Dubia roach.
Regarding other nutrients: Fat content is OK. Minerals are good. Calcium:Phosphorous ratio is poor and in absolute terms the Banded cricket has a lot of phosphorous, but most feeders are dusted with calcium anyway so it may not matter much. As long as you stay on top of dusting, the high phosphorous shouldn’t be an issue. It’s probably enough to be aware of the potential and keep an eye out for problems. As crickets are ubiquitous in the pet trade, so is Metabolic Bone Disease. While we don’t imply a causal link, we do note with certainty that crickets have not led to a reduction in that disease. So there’s that.
Dubia roaches beat crickets in a few nutrition-related areas like Ca:P ratio, chitin, percent protein, and minerals…but not by much. As previously mentioned, the Dubia’s protein is a fair bit higher than the Banded Cricket’s on a percentage basis because they have more meat and less water. The Banded Cricket wins on absolute calcium, but again, not by much. Fat is a toss up. Neither insect is particularly low or high and captive herp fat requirements aren’t very well studied, and they need some fat.
Dubia roaches have a nutritional advantage over Banded Crickets on paper. That advantage is not huge but it is something to consider. Where things really get interesting though is when you compare the practical aspects of dealing with these two insects in the real world. Sorry crickets. I’ll try to be as gentle as I can about this…
Crickets don’t have a pleasant odor. In fact, it’s fairly unpleasant, and it doesn’t take long for their enclosure to get pretty foul. I remember watching a show about cricket farming (external link) and I kept thinking “that place must smell awful”. If you’ve bred or fed crickets you probably know what I mean. Dubia roaches have very little smell and we’ve never heard anyone describe what little exists as “bad”. There’s just no comparison between the two.
Crickets are loud. I will give the Banded Cricket this though: they are far less noisy than standard house crickets. They still chirp late at night though. Jailbreaks are inevitable with feeder insects, and when crickets fly the coop they end up in places most people find hard if not impossible to reach. Walls, cupboards, and other structural units that can’t be moved come to mind. Between the Banded Cricket and the Dubia roach, the Dubia wins easily on noise. They make none – not counting the soft pitter-patter of tiny feet as they move about their enclosure.
As all experienced cricket-keepers know, cricket catching is an art. It’s one you’ll learn if you keep crickets. The trick, as we see it, is to anticipate their next jump and approach them with a cupped hand from the direction you suspect they’ll go next. When you get really good, they will often jump right into your palm and if you’re fast enough you just may catch one without squishing it. Don’t worry though. You’ll get the hang of it…if you buy crickets. You may even get so good at catching them that you invent your own technique.
On the other hand, Dubia roaches are a very slow-moving roach species. I wouldn’t call them “slow” per se, but they aren’t fast. When temperatures dip as they often do outside a herps enclosure, they get even slower. If the American cockroach was considered “the world’s fastest land insect” at one time, the Dubia roach must be its athletically challenged second cousin. Catching ones that get loose is rarely a problem. They don’t jump like crickets. In this regard there’s no equivalency between the two insects. Cricket escapees can be difficult and they may mock you with their chirp from behind walls. Dubia roaches are easy to catch, silent if they make it to freedom, and they won’t live long without high heat and plenty of food.
Running through the remaining issues quickly: Crickets will kill and eat other feeder insects and they can bite you and your animals. Their bite is not painful but animals are probably not thrilled about being nibbled on. Dubia roaches, on the other hand, don’t bite and they won’t nibble on your pets or other feeders. Cricket lifespan is a few months while Dubia roaches live a few years. Crickets have simple and short guts that process food in 24 to 48 hours while Dubia roaches have long digestive tracts and can keep food in their stomach for three days. They also have symbiotic relationships with special gut bacteria that produce vitamins and amino acids your animals can use from even very poor quality foods.
I’m trying to come up with something the Banded cricket does better than the Dubia roach, but I can’t think of anything. Again, I’ll admit my bias in favor of B. dubia, but I honestly want to think of something they’re good at. I suppose they are “easy” in the sense that you can buy them online or at the pet store, feed them off, repeat, and not worry about much else. But that kind of sounds like an appeal to tradition. I’m not sure that’s much of a defense. Animals enjoy eating them? It’s the same with B. dubia. They’re easy to feed and water but so are Dubia roaches. They are less expensive but animals typically eat far fewer Dubia roaches to get the same nutrition, and prices are coming down as they become more popular.
I don’t know. Dubia roaches win. Sorry crickets. As an aside, we use crickets as secondary feeders. We like them well enough for that. However, we find it a relief not to deal with them on a large scale. We’ve been there, and done that. They can be a source of anxiety, which we fully appreciated only after reducing their numbers. If they stopped making noise, smelling bad, and escaping as often and as easily as they do, we would consider revisiting our conclusion about the Banded cricket.
Tenebrio molitor is a very common and relatively inexpensive feeder that’s not just for reptiles, amphibians, and some arachnids, but also small mammals like rodents and sugar gliders. They’re also a particularly popular food for various wild and domestic birds. Mealworms are available from various online retailers, pet stores, and specialty feed shops where they’re often sold freeze-dried in bulk, by the pound.
With respect to nutrients, mealworms are middle of the pack in almost all the metrics on our feeder nutrition list. Protein, chitin, vitamins…they’re all perfectly average. If that was the end of the story they’d probably make a decent everyday feeder, but unfortunately for the mealworm (or perhaps fortunately), that isn’t the end of the story. Mealworms come up short in a couple key nutrients, which is why they’re more useful as treats than a dietary staple.
The mealworm’s trouble areas include calcium and fat. They have 22% the calcium and almost twice as much fat as Dubia roaches. In nature, larvae like the mealworm are difficult to come by. Of course mealworms don’t live in the tropics, but the point is that high fat insects are an energy bonanza to insectivores lucky enough to run into them, but that happens rarely enough that weight is not a problem. Problems occur when we feed handfuls of them to our animals. Birds, reptiles, amphibians, what have you – they all fatten up quickly on mealworms. It doesn’t take much and you have to be careful how many and how often they’re offered. On a positive note, they’re a very good contribution to dietary diversity, which is an understudied and probably under appreciated aspect of herp health. And, they make herps happy. Reptiles and amphibians in particular seem to really like mealworms. Mealworms make them happy, which makes us happy, so mealworms have a place in herp nutrition.
Mealworms are about as easy as Dubia roaches to keep and breed. They might even be a little easier because they don’t need high heat for breeding like B. dubia. They do fine at average room temperatures with a little grain as substrate and the occasional fresh vegetable for water. Like Dubia roaches, breeding them is a relatively hands-off affair. Their substrate and water source needs frequent changing, and attention to substrate moisture buildup is prudent. Unlike cockroaches, which are very social bugs that prefer and sometimes even need some measure of crowding (external link), mealworms should be separated by developmental stage to avoid cannibalization and to help the colony remain manageable. This is probably unnecessary for those with just a few they plan to feed off, but it is with any breeding setup or for long-term storage. Worms, pupae, and beetles need to be manually sorted. This can be tedious…and next to impossible with newly hatched micro-sized worms.
Mealworms can develop a bit of a smell if their numbers get large enough or their substrate is allowed to collect moisture. Mealworm beetles beetles give off a bit of a “stink” when disturbed, but their smell is not horrible and doesn’t linger. One of the relative issues we have with mealworms is that they don’t last long. The time can be counted in days and weeks rather than months, which is not at all like the Dubia roach. The worms you buy at the store are most often adults in varying stages of development, and pupae usually begin emerging shortly after you get a batch home. You may even have pupae before you walk out of the pet shop door. Their metamorphosis can be slowed down significantly by refrigeration, which is a good way to avoid virtually all the husbandry issues mentioned here. If you’re buying mealworms strictly as feeders with no interest in breeding, refrigeration is a very good choice.
Another drawback of mealworms is that they can’t be gutloaded in the typical way. Dubia roaches are extremely strong in this regard. In fact they might even be the most gut-loadable insect you can buy. Mealworms only eat a handful of grains as well as tiny amounts of vegetation for moisture. Not that these things aren’t healthy. In fact they are, but the scope of foods they’ll eat is very narrow. B. dubia will eat all the same foods as mealworms and thousands more. You can give them carrots and squash and collards and quinoa and fish meal and soy protein and bananas and mango, and the list goes on. Any vitamin and mineral you want your animals to eat and in virtually any combination, you can find a food or combinations of food that contain them that Dubia roaches will eat. And, as an added bonus, what they eat can stay in their stomachs for as many as three days. We have no idea how long food stays in mealworm stomachs, but since they don’t require action by special bacteria to break down foods and create vitamins and other nutrients, we’re guessing the time is not nearly as long.
All in all, mealworms are respectable. They’re fairly healthy, except for the few key nutrients they lack. And then there’s the fat. They’re easy to keep and breed, and animals tend to love them. They make a fantastic occasional treat. As a general feeder Dubia roaches win easily on nutrition. As an insect desert, we have to give it to the mealworm.
Zophobas morio, AKA the superworm or Kingworm, is not the same as the giant mealworm, which is simply a mealworm treated with growth hormones. Superworms are a totally different species. The two look similar – though superworms are larger and slightly darker in color – and they even share a few nutritional and husbandry traits. What they don’t share, however, is much in common with the Dubia roach. These two insects differ in significant ways.
Like mealworms, superworms are a high fat treat that animals love but are best served in moderation. In broad nutritional terms, we consider the two to be about the same. Superworms are larger which makes them a bit more convenient for mid-size and larger animals, but they’re higher in fat. They have less chitin than mealworms, but that’s balanced by more phosphorous and less available calcium. The two insects are essentially a wash compared to each other, but things get more dynamic when comparing the superworm and the Dubia roach.
Dubia roaches have three times more calcium than superworms and a third the phosphorous. That’s the wrong direction in both elements for the superworm. As a result it falls very near the bottom of the list in Ca:P ratio. Calcium dusting can make up for marginal deficiency, but at some point you have to stop and consider the food itself.
With respect to protein, superworms and Dubia roaches are similar. But, food is a package deal, and with the good you also take (and take in) the bad. Unfortunately for the animals and for us this fact is inescapable. Though comparable in protein, the Dubia roach is superior to the superworm in the remaining important categories, which include Ca:P ratio, calcium, fat, chitin, and minerals.
Keeping Dubia roaches and superworms as feeders is about the same in terms of ease and lack of hassle. Superworms might even be a bit easier because they can survive lower temperatures than Dubia roaches, which at minimum need about 70 degrees for most of the day. Breeding temperatures are even higher still for the Dubia, while superworms will reproduce at average room temperatures. Superworms breed faster at higher temperatures, but Dubia roaches will not breed at all below around 80 degrees F.
Superworm breeding is tricky but doable. They tend to eat each other – or more accurately, they tend to eat other superworm pupae, so they won’t pupate in proximity to each other. They have to be manually separated and that can be a pain with large numbers. However, when used as an occasional treat and raised as such – meaning in small numbers – they can actually be a lot of fun. Animals do love them, and they’ll love you for feeding them superworms the same way a kid loves you when you take them to eat at their favorite fast food restaurant. The twinkle in your animal’s eye totally makes up for the fact that the beetles stink when agitated even more than mealworms, and they need to be kept in a corner somewhere and not disturbed too often.
The larvae of Achroia grisella, and less commonly Galleria mellonella, are the two most common species of waxworms in the herp and pet food markets. Stores selling mealworms may also sell waxworms, but if not they are very easy to find and buy online.
It makes sense to jump straight to the bottom line with waxworms: This is another relatively unhealthy feeder that many animals love. Maybe they’re sweet from eating all that honey, or maybe it’s all that fat, but herps and other animals tend to go a bit crazy for waxworms. However, all the things that make them delicious are probably also the things that make them unhealthy…and they aren’t just nutritionally weak compared to the Dubia roach. They also fall short against almost all the other insects on our list. They have low calcium, a poor Ca:P ratio, low protein, high fat, and low minerals. In our opinion they’re only suitable as an occasional treat or as a small contribution to dietary diversity.
You want to be careful feeding waxworms to herps – not just because of their poor nutrition but because picky eaters can refuse to eat other more healthy insects if you overdo it with waxworms. If that happens and you give in, you’re kind of stuck. It’s like when a dog gets used to wet food…good luck switching to dry. Breaking a bad waxworm habit in a stubborn, finicky herp can be very difficult and time-consuming.
With respect to breeding, waxworms aren’t super easy but they’re not super difficult either. You need to get the right setup – honey, oats, bran or other substrate, beeswax, and plenty of patience. Unlike mealworms, waxworms are the caterpillar larvae of moths, so you need an arboreal breeding setup, and it follows that at some point down the road you’re going to be dealing with a fair number of flying insects. Chameleons in particular are often very excited by flying prey, so it can be fun to let a few waxworms pupate, but again….flying insects.
In the final analysis, waxworms require caution. Feeding them along with other insects once or twice a month is probably OK, but even then you have to be on the lookout for animals that start giving you a sad looks that say “but that’s not a waxworm…”
Bombyx mori, also known as the silkworm, is an interesting creature. It’s entire life-cycle takes only 50 days to complete, and in that time it transforms from a tiny egg to a mile-long silk-spinning caterpillar to a flightless moth that mates and dies within just hours of emerging from its cocoon.
We think that makes silkworms cool insects, but how do they stack up against B. dubia as a feeder? Nutritionally, silkies are basically a watered-down version of the Dubia roach. Literally. Silkworms have a very high water content. They contain a lot more fat and about the same protein as the Dubia roach on a dry matter basis, but because they’re third from the top in water content, they come in third from last in protein as a percentage of nutrients. They’re in the middle of the pack with respect to fat.
We think this takes them out of the running as a primary feeder insect, and in our view there isn’t much in the vitamin or mineral department to redeem it. They are average to low in most of the nutrients we want more of, like calcium and vitamin A. They are also high in a few things we don’t want, like chitin. As such, silkworms are a good choice as a temporary food for dehydrated animals, and herps tend to enjoy them so they make great treats, but they’re generally not on the radar as an everyday feeder.
On the up-side, keeping silkworms isn’t particularly difficult. They can be finicky at times and may require effort, but breeding them is doable.
We think silkworms are similar to mealworms in some ways. You buy them, feed them, they spin a cocoon (instead of turning into a beetle), then some weeks later you have eggs. Then the whole process starts over again and soon you have a bunch of “worms” of various sizes for your animals. As previously mentioned though, silkworms are not exactly hands-off breeders. Their dietary and environmental needs are more specific than mealworms.
For example, silkies – for all intents and purposes – only eat one food, and that is the leaf of the mulberry tree. If you have access to mulberry trees you’re in luck…except they’re deciduous and you won’t have leaves six months out of the year. In that case you have to buy special food made from mulberry leaves, or maybe freeze your own.
Like Dubia roaches, silkworms prefer temperatures near 85 degrees to hatch and grow – though silkworms can handle lower temps as they grow larger. That comes at a cost though, which is that they are very fragile for the first week or so after they hatch and many don’t survive.
And that’s basically it. You can breed silkworms, but they take a good deal of care. It may involve incubators and a lot of hands-on work for each individual caterpillar. As such, you generally don’t get high production out of silkworms. They’re best suited as an occasional treat for most reptiles and other herps anyway because they’re high in fat and chitin and low in protein and all the micronutrients, which in our view disqualifies them as an everyday feeder. From our perspective it makes the most sense to buy the occasional batch of silkworms or butterworms or hornworms as a treat, keep them around until they’re fed off, then think about another insect treat a few weeks down the road.
The Giant Mealworm
Tenebrio Molitor, aka the mealworm, can be hormonally manipulated to grow larger than it would under normal circumstances. Giant mealworms are not superworms. Those are a different species. They are just regular mealworms that have been exposed to growth hormone for a longer period of time than normal.
We have not tried raising giant mealworms, but aside from the hormone-related treatment we assume it’s the same as breeding regular mealworms. We know they start off the same. They are the same insect eating the same food and living in the same conditions. At some point they are exposed to some chemical or condition that prevents the drop in growth hormone that precedes pupation. This results in a mealworm that just keeps growing and growing – up to about an inch and a half.
Size-wise, giant mealworms are midway between regular mealworms and superworms. Their nutritional profile appears to be about the same as regular mealworms. There is one exception though, and that is that giant mealworms seem to have a better calcium:phosphorous ratio than regular mealworms. We aren’t sure why that would be, but that’s what the research shows.
All of the other nutrients and metrics are substantially similar for both. That means that like mealworms, giant mealworms have average nutrition but are high in fat, making them more suited as treats or auxiliary feeders but they probably should not make up the bulk of an animal’s diet.
Chilecomadia moorei, better known as the butterworm, is the larvae of the Chilean Moth. In Chile they are called Trevo Worms because they can be found locally feeding on the leaves of the Trevo bush.
Nutritionally, butterworms are similar to waxworms and mealworms and the like, but they’re lower in protein and, importantly, fat. They also have a fair amount of calcium, which is a big plus in our book. Given these favorable nutritional properties we think butterworms may have some potential as a secondary feeder insect. Unfortunately though, they are impossible to breed at this time. And they are expensive. They’re also not reliably available.
Because they can’t be bred, we think they’re best fed to animals as treats. They are more nutritious than many of the other “worms” and that makes them intriguing, but their nutrition isn’t so spectacular that it overcomes the butterworm’s other limitations, which are most notably the inability to breed and sporadic availability. However, they do keep quite well in the refrigerator for a month or two, and that makes it very tempting to slide them permanently into the “treat” category. We can buy a batch or two and feed them off over time without worrying about waste.
While we might consider breeding butterworms if we could, we don’t think we’re really missing out on much by not. As mentioned, they are nutritionally similar to mealworms and superworms, and where those lack calcium we can supplement with dusting. Calcium is a mineral so it doesn’t need to be in a bug to be good. And mealworms are so easy to grow that the little extra nutrition our animals get from butterworms isn’t worth much more than the occasional trip to our local herp shop for a few dozen.
As far as we know, all butterworms in the US are imported from Chile. As a rule, they irradiate all of their exported butterworms. Because they are irradiated, and because they appear to eat only one type of plant that happens to be native to Chile, it isn’t possible to breed them as feeders locally.
As for why butterworms are irradiated before export, we were unable to find any official information to explain it. The USDA says “irradiation treatment prevents the larvae from molting to an adult” (external link), but it doesn’t mention why.
We import a lot of agricultural products from Chile and none are required to be irradiated. That butterworms are seems curious. Because butterworms eat only one plant that is local to Chile, and because they seem to only breed in certain conditions, it seems unlikely that they are an infestation risk as some people speculate.
It seems more likely that butterworms are sterilized to protect the Chilean butterworm industry. If we could breed them we wouldn’t need to import them. That’s just a guess though. We really can’t say for sure.
So where does that leave us? Buying the occasional batch of butterworms and storing them in the fridge until they’re all eaten up. Our reptiles don’t seem to care about the political milieu or economic protectionism. They just know they like butterworms a lot.
Black Soldier Fly larvae
Hermetia illucens, aka: the black soldier fly, is a short-lived, harmless, “wasp-like” fly. It is commonly used as a feeder insect while in its larvae stage, where it stays for several weeks before pupating, then morphing into its fly form.
As far as feeders go, the larvae itself is small, measuring about a half to three-quarters of an inch in length. It is most commonly used to feed small chameleons, geckos and other reptiles, and amphibians. It is not commonly used as a feeder insect for arachnids due to its high calcium content.
The black soldier fly is found naturally in coastal states from the mid-East coast down through the south, along the southern US/Mexico border, and up the West Coast to the border of US and Canada. It requires steady heat and cannot survive cold temperatures, so it is not generally found in areas subject to prolonged periods of freezing winter temperatures.
Black soldier fly larvae is widely available online via mail order. It is a popular feeder for several reasons: First, it’s easy to find in the wild, easy to breed, and easy to feed. For those who live in the right climates, they proliferate quickly and require no special equipment to keep and breed. They can be found in most backyard compost piles in the Southern United States, and all they require to breed and thrive is a steady source of rotting plant matter or manure. These factors make them generally inexpensive.
Second, their main selling point is that they’re very high in calcium. And by very high, we mean very high. According to currently available data, black soldier fly larvae has more than 20 times the calcium of its nearest insect competitor, which happens to be the earthworm. That’s 2000% more calcium than the next feeder! If your animals are low in calcium, this insect will certainly provide a boost, and then some. And, the black soldier fly also has a favorable calcium:phosphorous ratio, which helps with calcium absorption and utilization.
Those are the main selling points: wide availability and high calcium. Husbandry is easy: it’s not a pest, it’s commonly found in parts of the US, and if you can keep a bucket of compost you can keep black soldier fly larvae. Keeping them in any real quantity may require creating an enclosure to keep flies in and pests out, but that wouldn’t have to be elaborate and could be rigged fairly easily. Basically, you provide them with food and an area to eat and live, and the two are basically the same thing, and that’s about it.
Regarding nutrition, black soldier fly larvae has average protein compared to other feeders. And, it’s high in fat. With the exception of fat in the waxworm, all other “pupae” feeders have more protein and less fat than black soldier fly larvae. Again though, they’re super high in calcium, and they make tasty treats…but on their face they aren’t really primary-feeder material.
They also have low-ish chitin content, which makes them a good choice for young animals with sensitive digestive systems. It has more chitin than B. dubia, but at this point it’s probably more appropriate to compare black soldier fly larvae with other pupae feeder insects, with which it shares (relatively) common traits. If you want a pupae feeder, nutritional analysis is really a mix-and-match of different protein, fat, chitin, and calcium levels. Some other nutrients can be compared too, but these are the main four.
While the black soldier fly’s high fat and low-ish protein may be OK for some animals, but the calcium may cause problems in the long-run. Calcium is a mineral, and if an animal is low it’s easy enough to supplement with a calcium/phosphorous dust. Calcium is the same regardless of where it comes from, so in our view black soldier fly larvae is best used as a treat or as a supplement to a primary feeder.
Comparing the black soldier fly larvae to the Dubia roach…is really an unfair comparison. The two insects are in totally different leagues. Since black soldier fly larvae lives in compost, it may be inherently gut loaded upon feeding. That’s a plus, and it may account for its favorable mineral content. As nasty as compost is, it’s a rich source of nutrients…for insects that are into that kind of thing. But the bottom line is that you have to be careful with black soldier fly larvae because of their high calcium. It’s easy to go overboard with them, and you should avoid that.
And, they’re also relatively small. Dubia roaches can grow several inches long and weigh as much as 20 black soldier fly larvae, so again, the black soldier fly is limited to small animals where Dubia roaches range in size from pinhead cricket to two inch monsters. Feeding a small handful of black soldier fly larvae to bearded dragons, for example, can be fun, but at some point you’re likely to find yourself wanting for a more size-appropriate insect.
This one wasn’t really a fair fight, but that’s OK. As a feeder, black fly larvae has its place. They’re cheap, foraging food for your animals naturally can be fun, and feeding the occasional black soldier fly larvae to your animals can take care of the calcium needs. They’re a treat, but they’re not primary feeder material. Maybe they can be main feeders for fish in a pond or chickens in the backyard, but not herps.
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