This guide provides in-depth nutrition content and husbandry information for insects commonly fed to captive insectivores, including reptiles, amphibians, and arachnids.
It’s divided into two main sections: (1) Insect nutrition and (2) head-to-head comparisons. “Insect nutrition” contains in-depth nutrition data for 20 insects, compiled from many authoritative sources. The “Head-to-head comparisons” section is where we compare the insects to Dubia roaches.
Table of Contents:
- Insect nutrition data
- Head-to-head comparisons
- Sources and references
The “data” section contains insect nutrition information. We got this information 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 organized the results in sortable tables to make it easy to compare and contrast the various insects.
The results come from pooled, normalized data that we boiled down to something meaningful so pet owners could use it to make real-world decisions about which insects to feed their animals. Do you want to know which bug has the most calcium or the highest Ca:P ratio? No problem. You can sort the data by your metric of choice to see how the insects compare.
The “head-to-head” section also compares insect nutrition, but it goes far beyond that. It also looks at care & keeping and what it’s like to feed your animals one insect versus another. We wanted to address differences among feeders from the perspective of both the animal and the owner.
We hope to give you a sense of what it’s like to feed, keep, and breed each insect, and we also compare each insect to the Dubia roach. Essentially, we use B. dubia as a benchmark. This allows us to draw contrasts between not just each insect species and the Dubia roach but indirectly between each species.
While each match-up touches on nutrition, the goal is to provide a realistic idea of what issues you might encounter after bringing each insect home. Did you ever try breeding crickets only to find they smell horrible after a few weeks? This is the type of issue our head-to-head comparisons address and more.
The goal, in short, is to help you choose the best feeder insects for both you and your animals, given your unique situation.
Feeder insect nutrition and husbandry
Practically speaking, insect nutrition and husbandry are inseparable. It makes little sense to buy a super-nutritious insect if you can’t house it, and there’s not much to gain from feeding your animals insects that are easy to keep and breed but have no nutritional value.
We created this guide 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 nutrition profile and personality. Each animal has specific nutritional needs. And each animal owner has a set of circumstances they work within. The closer the fit between these three things, the better your experience with your animal will be.
With insectivores, nutrition is among the top concerns for both amateur and professional caretakers. Unfortunately, reptiles, amphibians, arachnids, and other animals tend to suffer health problems in captivity. Many of these problems are related to diet.
As you probably know, a nutritionally deficient diet can cause serious and sometimes irreversible health problems in insectivores. For example, calcium deficiency can lead to Metabolic Bone Disease. Hypovitaminosis-A can develop when vitamin A is lacking. The list of diet-related health problems is long. All animals need a reliably nutritionally adequate diet and captive animals often don’t get what they need. And some animals are more vulnerable than others. Young, growing animals need more nutrients than older ones, and reproduction significantly increases an animal’s nutrition requirements.
In the wild, dietary diversity solves this problem. This is true even in cases of scarcity. The problem is reversed in captivity: Lack of food is rarely a concern, but lack of food diversity is.
For these reasons, you need to get your animal’s diet right. It’s important. This is why we compiled data for not just a few insects but 20 of the most commonly available feeder insects 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 commonly fed to insectivores that may live in your area. If this article inspires you to do a little hunting, you may find one or two of the native species in your own backyard. Not that we advocate feeding captive insectivores wild insects…but we acknowledge that people do it.
While compiling this data, we decided to take the next step and create individual head-to-head comparisons between 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. Feeder care & keeping is part of the deal, and you should be aware of issues about diet, noise, odor, and cleanliness before deciding on an insect, not after. Some bugs can aggravate 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 because we wanted to give you a sense of which insects may work for you and which ones may not before you purchase them.
Lack of information
For such basic and we think useful information, its scarcity surprised us. When we first got into Dubia roaches, we searched online for anything that might help us understand more about insect and insectivore nutrition. However, most of what we found was incomplete and unreliable. Much of it was contradictory. It didn’t seem credible because it was not sourced and seemed suspiciously self-serving. The unsourced claims were often repeated by many websites, and the basis for those claims was not just unknown, but we questioned whether it ever existed in the first place.
For this article, we weren’t interested in hype. In fact, we wanted the opposite. Our goal was to create reliable data from basic research and other primary sources that we could use to make better 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’s worth noting that nutrition information for the same insect species often differs between sources. Occasionally, it differs a lot. There may be several reasons for this. Age, sex, diet, life stage, reproductive status, and environment contribute to an insect’s nutritional status.
When we found differences in the data, we tried to understand what caused those differences. Occasionally, we got lucky, and something like statistical insignificance due to the small sample size accounted for outliers in the data. Other times, we could discount data because the methods researchers used were questionable.
However, there were occasions when we couldn’t discount data or explain the significant differences between studies and data. In these cases, we did our best to weigh the outlying data and then include it in the results.
That said, our results are not scientific, but we think they’re pretty good. They’re certainly good enough to be the basis for the decisions we make for our animals.
Acknowledging our bias
Finally, we want to acknowledge our bias. We sell Dubia roaches. This should be obvious. We think Dubia roaches are the most nutritious and user-friendly feeder insects available. This is why we began feeding them to our animals and why we started breeding them.
However, we are interested in the truth. That’s why we got into Dubia roaches in the first place. We think the best advertising is the Dubia roach itself. Its quality is clear to us. We see it in the data and in our daily lives. So throughout our website, we provide the information that helped us form our opinions about this remarkably nutritious insect. Of course, we hope you agree, but every situation is different. Ultimately, we want you to make the best choices for yourself and your animals. And here is some of the data we think you need to do it.
The insect nutrition data
NOTE: One or both of the tables below are sortable by column heading, if your browser supports it.
|Black Soldier Fly Larvae
|Black Soldier Fly Larvae
As an aside, the nutrition information above is more practical when you know the dietary needs of the animal(s) you’re keeping. It’s not a 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 be mindful of this information when deciding what and how to feed insectivores. Because so few insects fall outside these 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.
We understand many animals don’t do well when fed just one feeder insect. We also know many don’t do well on high-fat diets. Using what is known in practice alongside what research tells us may be a good approach here.
Head-to-head: The husbandry comparisons
This section provides a sense of what it’s like to keep, feed, and breed each top feeder insect compared to Dubia roaches. Since much of the experience of keeping various insects is situational, these comparisons are relative by design. We think that’s the best way to analyze and convey this information. While it’s difficult to quantify a characteristic like smell, comparing smells produced by two different insects is not hard. Most people can understand relative ranking, particularly those with experience raising or feeding some of these insects.
While the previous section focused on data, this section explores contrasts. What distinguishes these insects from B. dubia? Where are they similar, and when do they differ? Are there any similarities, or is the relationship defined by differences? This section is about personalities. But not just that…it’s about relative personalities. We make nutritional comparisons here, but we keep them brief because they’re mostly incidental to what we’re trying to convey. You can already find those details in the tables above.
The Dubia roach vs…
The American Cockroach
Periplaneta americana and Blaptica dubia are a lot alike. This makes sense. They are both cockroaches from the same Order. They have similar body composition and grow to about the same size (though B. dubia is slightly bigger). There are even similarities in the macronutrients, vitamins, and minerals they offer as feeders. However, their similarities relate almost exclusively to nutrition and 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, very few are inhospitable for the American cockroach. Of course, this means there is potential for infestation. And American cockroaches are very fast. In fact, they’re not only one of the fastest cockroaches but one of the fastest land insects in the world (external link). If you’re worried about an infestation, steer clear of the super-fast land speed world record holder. And unlike the Dubia roach, American cockroaches can fly. Both males and females are able to fly when conditions are right.
For those who decide to keep American cockroaches as feeders, the other notable differences between the two species are odor and longevity. American cockroaches have an odor that is stronger and more acrid than their Dubia counterpart. The smell is not horrible, but it’s noticeable. Dubia enclosures often smell like whatever food they’ve recently eaten, plus a slightly musky scent that they emit when disturbed. In the grand scheme of things, neither smell is bad, per se. But when compared to other feeder insects, one could argue that Dubia roaches smell “good.” Remember, this is a relative comparison. More on that later…
Regarding longevity, female Dubia roaches live for about two years. American cockroaches live for about 18 months.
And finally, since some insectivore owners like self-caught insects — a word of caution here. At times of food scarcity, cockroaches will eat almost anything. This includes things that are not good for animals. We don’t recommend catching and feeding wild roaches to your animal(s) 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’ve eaten can stay 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 mostly Gryllus assimilis.
Crickets are ubiquitous in the pet trade. They are as mainstream as it gets. These days, crickets are sold at big-box stores like Petco. It was not 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 are just OK. Compared to other insects one might consider feasible to sell on a large scale, crickets are reasonably good. They have a fair amount of protein on a dry weight basis, though a high water content means much less protein on a per-cricket basis. This reality of Banded cricket nutrition density may explain the common experience reptiles and other animal owners have where animals fill up on, say, a dozen crickets per day while only needing one or several good-sized Dubia roaches.
With respect to other nutrients, fat content is OK. Minerals are good. The calcium-to-phosphorous ratio is poor. And in absolute terms, the Banded cricket has a lot of phosphorous. But most people dust their feeders with calcium anyway, so it may not matter much. High phosphorous may not be an issue if you dust often. 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 mentioned before, the Dubia’s protein is a fair bit higher than the Banded Cricket’s protein 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 insectivore fat requirements are not well-studied. And they do 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 is when you compare the practical aspects of dealing with these two insects in the real world. Sorry crickets. We’ll be as gentle about this…
Crickets have an unpleasant odor. In fact, they smell bad, and it doesn’t take long for their enclosure to become foul. Many have seen the “dirty jobs” show about cricket farming (external link). That place must smell awful. If you have bred or fed crickets, you probably know. Dubia roaches have very little smell, and we’ve never heard anyone describe what little exists as bad. Regarding the smell of crickets and Dubia roaches, there is no comparison.
Also, crickets are loud. However, we will give the Banded Cricket this: they are far less noisy than standard house crickets. But they chirp late at night. Jailbreaks are inevitable with feeder insects, and when crickets fly the coop, they end up in places most people find hard or sometimes impossible to reach. Walls, cupboards, and other structural units that can not be accessed or 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 — one you will 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 it will go next. When you get really good at catching crickets, they’ll often jump right into your palm, and if you’re fast enough, you just might catch one without squashing it. Don’t worry though — you’ll get the hang of it. 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. They aren’t slow per se, but they aren’t fast. When temperatures dip as they often do outside an animal’s enclosure, Dubia roaches 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 is no equivalency between the two insects. Cricket escapees can be difficult, and they may mock you with their chirps 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. 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 certain gut bacteria that produce vitamins and amino acids your animals can use, even from very poor-quality foods.
In trying to come up with something the Banded cricket does better than the Dubia roach, we can’t think of anything. Again, we’ll admit our bias in favor of B. dubia, but we’re trying to come up with something they’re good at. They are easy, in the sense you can buy them online or at a pet store, feed them off, repeat, and then not worry about much else. But that sounds like an appeal to tradition. This isn’t much of a defense. Do animals enjoy eating them? It’s the same with Blaptica dubia. Crickets are easy to feed and water, but so are Dubia roaches. And crickets are less expensive, but animals typically eat fewer Dubia roaches to get the same nutrition. Dubia roach prices will decline as they become more popular.
In a race between Dubia roaches and crickets, we think 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 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 popular food for various wild and domestic birds. Mealworms are available from 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 the 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 would 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 few important nutrients, which is why they’re more of a treat than a dietary staple.
The mealworm’s trouble areas include calcium and fat. They have 22% calcium and almost twice as much fat as Dubia roaches. In nature, larvae like mealworms are hard 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 across them. But this happens rarely enough that their high-fat nature is not a problem.
Problems do occur, however, when we feed handfuls of fatty insects to our animals. Birds, reptiles, amphibians, what have you — they all fatten up quickly on mealworms. It doesn’t take much, so be careful how many you offer and how often. On a positive note, they contribute nicely to dietary diversity, which is an understudied and probably underappreciated aspect of insectivore health. And they make animals happy. Reptiles and amphibians particularly seem to really like mealworms. When mealworms make our animals happy, that makes us happy, so mealworms have a place in insectivore 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 grain as substrate and the occasional fresh vegetable for water. Like Dubia roaches, breeding mealworms is a relatively hands-off affair. Their substrate and water source need 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. Their beetles give off a bit of a “stink” when disturbed, but their smell is not horrible and doesn’t linger. Mealworms don’t last long relative to Dubia roaches. Time can be counted in days and weeks rather than months, which is very different from Dubia roaches. The worms you buy at the store are most often adults in varying stages of development, and pupae usually begin emerging soon after you get a batch home. You may even have pupae before you leave the pet store. Their metamorphosis can be slowed down significantly by refrigeration, which is a good way to avoid virtually all the husbandry issues mentioned here. Refrigeration is recommended if you buy mealworms strictly as feeders with no interest in breeding them.
Another drawback of mealworms is that they can’t be gut-loaded in the usual 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 and a small amount 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, squash, collards, quinoa, fish meal, soy protein, bananas, mango…and the list goes on and on.
Any vitamin and mineral you want your animals to eat, and in virtually any combination, you can find food or combinations of foods 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 reasonably healthy, except for the several key nutrients they lack. And then there’s the fat. They’re easy to keep and breed, and animals often love them. For these reasons, 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. However, they don’t share 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 than superworms, making them more convenient for mid-size and larger animals, but are 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 of the phosphorous. That’s the wrong direction for both elements in 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 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 below about 80 degrees F.
Breeding superworms is tricky but doable. Superworms tend to eat each other, so they won’t pupate near others. They have to be manually separated, which can be a pain with large numbers. However, when used as an occasional treat and raised as such, superworms can be fun. Animals do love them, and they’ll love you for feeding them superworms much the same way a child loves to be taken to 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.
Larvae of Achroia grisella, and less commonly Galleria mellonella, are the two most common species of waxworms in the pet food market. Stores selling mealworms may also sell waxworms, but if not, they are 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’s loved by many animals. Maybe they’re sweet from eating all that honey, or it’s the high fat, but insectivores 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 Dubia roaches. They also fall short against almost all the other insects on our list. For instance, they have low calcium, a poor Ca:P ratio, low protein, high fat, and low minerals. We consider them best suited as an occasional treat or a small contribution to dietary diversity.
You want to be careful feeding waxworms to your animal(s) — not just because of their poor nutrition, but because they can cause picky eaters to refuse to eat other healthy insects if they are fed waxworms too often. If that happens and you give in, you may be stuck. It’s like when a dog gets used to wet food; good luck switching to dry. Breaking a waxworm habit in a finicky animal can be difficult and time-consuming.
With respect to breeding, waxworms aren’t easy, but they’re not super hard either. You just need to get set up with 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 excited by flying prey, so it can be fun to let a few waxworms pupate around a chameleon. 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 then you have to watch for animals demanding only waxworms. You’ll know when they give you that telltale sad look that seems to say, “…but that’s not a waxworm.”
Bombyx mori, also known as the silkworm, are interesting creatures. Their entire life cycle takes only 50 days, and in that time, they transform from tiny eggs to mile-long silk-spinning caterpillars to flightless moths that mate and die within just hours of emerging from their cocoons.
We think that makes the silkworm a cool insect, but how does it stack up against B. dubia as a feeder? Nutritionally, silkies are basically a watered-down version of the Dubia roach. Literally. The silkworm has a very high water content. It contains significantly more fat and about the same protein as the Dubia roach on a dry matter basis. But because it’s third from the top in water content, it comes in third from last in protein as a percentage of nutrients. The silkworm is 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 temporary feeders for dehydrated animals. And because animals tend to enjoy them, silkworms make great treats. But they aren’t on our radar as everyday feeders.
On the upside, keeping silkworms isn’t particularly difficult. They can be finicky 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), and then some weeks later, you have eggs. Then the whole process starts over again, and you have a bunch of “worms” of various sizes for your animals. As previously mentioned, silkworms are not 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: 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 need to buy special silkworm 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. They are fragile for about the first week after hatching, 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 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 insectivores anyway because they’re high in fat and chitin and low in protein and all the micronutrients, which disqualifies them as an everyday feeder, in our view. From our perspective, it makes the most sense to buy an occasional batch of silkworms, butterworms, or hornworms as a treat, keep them around until they’re fed off, and then think about another insect treat a few weeks down the road.
As a project though, if you’re into it, we say go for it. But be sure to not go overboard on any high-fat, low-protein feeder.
The Giant Mealworm
Tenebrio Molitor, aka the mealworm, can be hormonally manipulated to grow bigger than it normally would. Giant mealworms are not superworms. Those are a different species. They are just regular mealworms exposed to growth hormones for longer than usual.
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 insects 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 — 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, which is that giant mealworms seem to have a better calcium to 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.
If you want to try raising mealworms, we say go for it. If you figure out the hormone thing, let us know! We are curious to know how it’s done.
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, mealworms, and the like, but they’re lower in protein and 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 keep quite well in the refrigerator for a month or two. This makes it tempting to slide them 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 them 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 pet 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 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 didn’t 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 many agricultural products from Chile and do not require irradiation. That butterworms are irradiated 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.
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 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 in its larvae stage, where it stays for several weeks before pupating and then morphing into its fly form.
As far as feeders go, the larvae are small. They measure about a half to three-quarters of an inch in length. They are most commonly fed to small chameleons, geckos, and other reptiles and amphibians. Black soldier fly larvae are not commonly fed to arachnids due to their 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 the 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.
Black soldier fly larvae are 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 living in the right climate, black soldier fly larvae 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 need 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 have more than 20 times the calcium of their 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 provide a boost, and then some. The black soldier fly also has a favorable calcium-to-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, and it’s commonly found in many parts of the US. And if you can keep a bucket of compost, you can keep black soldier fly larvae. Breeding them in any 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 live, and that’s about it.
Regarding nutrition, black soldier fly larvae have 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, 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 a mix-and-match of different protein, fat, chitin, and calcium levels. Some other nutrients can also be compared, but these are the main four.
While the black soldier fly’s high fat and low-ish protein may be OK for some animals, the calcium may cause problems in the long run. Calcium is a mineral. It’s easy to supplement with calcium and phosphorous dust if an animal is low. Calcium is the same regardless of where it comes from, so in our view, black soldier fly larvae are best used as a treat or a supplement to a primary feeder.
Comparing the black soldier fly larvae to the Dubia roach seems a bit unfair. The two insects are in totally different leagues. Since black soldier fly larvae live in compost, they may be inherently gut-loaded upon feeding. That’s a plus, which 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, 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’ll find yourself wanting a more size-appropriate insect.
This one wasn’t really a fair fight, but that’s OK. As a feeder, black fly larvae have their 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 their 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 reptiles, amphibians, or arachnids.
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