As an example of the potentially rich and productive field of exploration and discovery that can be reached through the integration of studies that tie the basic science and practical/applied aspects of insect rearing systems and their components, let me explain an example that I use in my insect rearing classes.

This narrative is based on an unpublished investigation that I did in my laboratory in recent years. I found a series of papers from the laboratories of Professors VandenBrooks and Harrison, including the paper by VandenBrooks et al. 2018 where the authors show that oxygen deficits for developing Drosophila melanogaster led to dramatic compensatory changes in the flies’ tracheal system and mitochondria. Though my background includes more 50 years of experience in physiological ecology, including studies of gas exchange, I was amazed at the profound effects that oxygen deprivation (holding developing larvae at about 10% O₂) on the fundamental respiratory components of the flies. My amazement at the findings of this study led me to ask the question: how often do we find conditions in our rearing systems where the insects are being O₂  -deprivation stressed (and likewise excess CO₂ stressed)? I approached two of my colonies (painted lady butterfly larvae) with this question and with an instrument that measures headspace O₂ and CO₂, and I found a fairly small difference between rearing container gases and those in open laboratory air in my painted lady butterfly larvae cages; HOWEVER, in my waxworm cages I found that the O₂  reading was about half that of laboratory air, and CO₂ was about 180 times that of laboratory air (90,000 ppm vs. 500 ppm in lab air). The waxworm cages were modified Ziplock food storage containers with 24 pinholes in the lidding made with conventional dissecting needles (Figures 1 and 2).

Figure 1 (top), Ziplock container of waxworms (Galleria mellonella): container lid had 24 pinholes for gas exchange and Figure 2 (bottom), an O₂ and CO₂ headspace analyzer showing 10.7% O₂ and CO₂ at 9.0% or 90,000 ppm.

The first hypothesis that this question generated was that providing larger openings for gas exchange would improve the contents of O₂ and CO₂ and that in turn, a higher O₂ and a lower CO₂ would reduce stress and enhance the fitness of insects with improved gas exchange systems. I tested the first part of my hypothesis by placing 2 x 2 cm openings in the cage tops of the waxworm containers, replacing the cutout plastic with stainless steel mesh that was very porous (Figure 3). The comparison of the improvements can be seen in Figure 4, and preliminary observations of faster growth rates seemed to support the 2^nd part of my hypothesis, but this hypothesis will require more testing. 

The point of this narrative is that the dramatic findings from the VandenBrooks paper prompted me to do some deep thinking about how much we take for granted that our containers are doing their job of providing adequate oxygen and removal of excess carbon dioxide; but with insects that are densely packed and/or of high metabolic demands (such as waxworms), this lack of attention may be a basis for cryptically stressed insects. 

This preliminary study is a good example of the kind of linking studies that the Special Topics Collection is striving to publish in order to help the rearing community appreciate the value of basic science studies of the biological and physical aspects of rearing systems and how these data-driven, science-based inquiries can lead to improvements in the rearing conditions in terms of food, gas exchange, environmental features, and all other aspects of reliable insect rearing systems.

The MDPI journal Insects is publishing a Special Topics series on insect rearing science with a special focus and emphasis on papers that at once contribute to the basic science behind rearing while making practical contributions to rearing technology. Please note the announcement of the Special Issue and the explanation here:

Please note that we will be extending the deadline for six months. If this type of research is of interest to you, please consider doing a research or review paper that fulfills the mission of showing and telling WHAT rearing technology will help improve insect rearing as to what kinds of rearing systems components and processes are of value leading to production of insects that are highly fit and/or of high quality. And also, the intended papers will explain the WHY and HOW of the rearing system inquiries work. In other words, we are seeking scientific inquiry that taps deeply into basic science while it shows the applications of that science. A crucial part of the welcome papers is that they are based on .explicitly-stated rationale. Here are some examples to suggest the kind of dual function papers, we are seeking for the Special Issue.

I have presented here 1) a background paper the provides basic science and then 2) a possible rearing improvement paper that connects the basic discovery to a practical rearing application.

Potential examples

1. Omega 3 unsaturated fatty acids effects on learning and brood rearing in beesimprovement of various fitness parameters in reared insects (weight, development rate, fecundity, etc. (see reference 1)
2. Improving containers to increase gas exchange efficiency Increase in various biological fitness measures (growth rate, fecundity, survival, antimicrobial defenses, etc. (see reference 2)
3. Hypoxia affects growth rate ample supply of O2 and improvement of growth and development rate (and other biological parameters such as fecundity and survival) (see reference 3)
4. Carotenoids and vision improvements in fitness resulting from addition of key carotenoids and related pigments (see reference 4)
5. Dietary protein quality and immune functionability of reared insects to withstand exposure to microbial growth in rearing system. (see reference 5)
6. Wolbachia (bacteria) affect reproductive performance in Wolbachia-compatible vs. incompatible strainsDetection and then manipulation of Wolbachia in colonies. (see reference 6).

References:

1. Fabian A. Ruedenauer, Alexa Aline Schaeffler, Tim Schneider, Gabriela Rakonic, Johannes Spaethe, Sara D. Leonhardt. Does fat identity matter? The effect of saturated and unsaturated fatty acids on bumble bee consumption and fitness. Ecological Entomology. 50: 318-328. 2025.
2. VandenBrooks, J.M. et al. Supply and demand: how does variation in atmospheric oxygen during development affect insect tracheal and mitochondrial networks. J. Insect Physiol. 
3. Acute and chronic effects of atmospheric oxygen on the feeding behavior of Drosophila melanogaster larvae. Manoush Farzin, Todd Albert, Nicholas Pierce, John M. VandenBrooks 1, Tahnee Dodge, Jon F. Harrison. J. Insect Physiol. 68 (2014)
4. Reinecke, J. P. 1991. Increased field trap capture of the mass-reared boll weevil (Coleoptera: Curculionidae) fed diet supplemented with beta-carotene. J. Econ. Entomol. 84 (2): 633-637
5. K. P. Lee, S. J. Simpson and K. Wilson. Dietary protein-quality influences melanization and immune function in an insect. Functional Ecology 22. 2008.
6. Steen Christensen, Moises Camacho, Zinat Sharmin, A. J. M. Zehadee Momtaz, Laura Perez,Giselle Navarro, Jairo Triana, Hani Samarah, Michael Turelli, and Laura R. Serbus Quantitative methods for assessing local and bodywide contributions to Wolbachia titer in maternal germline cells of Drosophila. MC Microbiology https://doi.org/10.1186/s12866-019-1579-3

In my previous post, I discussed the benefits of stating explicit rationale for rearing advancements (diet or other rearing system components development and improvement as well as developing SOPs). In the current post, I will guide readers through an example of a HOW and WHY type of inquiry.

We discover HOWs and WHYs of materials and processes by doing experiments. For years, my research (from about 1975-2010) was done in the old “one factor at a time (= OFAT)” experiments. My progress was slow, time consuming, and IT NEVER GAVE ME MUCH INSIGHT INTO INTERACTIONS IN MY EXPERIMENTAL REARING SYSTEMS. In writing my first book: Cohen 2003, Insect Diets: Science and Technology, CRC Press Boca Raton, FL, I wrote that diet experiments (and by implication other kinds of rearing experiments) must be done one factor at a time; but a colleague from the USDA, Agricultural Research Service, Dr. Steve Lapointe wrote a criticism of my OFAT statement and excellently pointed out [Lapointe, S. L., T. J. Evens, and R. P. Niedz. 2008. Insect diets as mixtures: optimization for a polyphagous weevil. J. Insect Physiol. 54: 1157–1167. ] the insect diets are mixtures, and as mixtures they could be treated with multiple factor designs such as design of experiments (which was originated about 75 years before my insect diet book). [background on R.A. Fisher’s works on multiple factor experiments: R.A. Fisher book: Design of Experiments. 1935. Edinburgh: Oliver and Boyd Ltd. Pp. 1-252. Amazingly, the 1935 Fisher book was an outgrowth of Fisher’s earlier works on engineering of optimization from the mid-1920s (Box, J. F. (1980). “R.A. Fisher and the Design of Experiments, 1922-1926” The American Statistician. 34 (1): 1–7. doi:10.2307/2682986 – via JSTOR.)]

This leads to my approach to understanding the HOWs and WHYs or discovery of the nature of Yamamoto Diet components as they interact in the diet, taking us back to the design of experiments inquiry that I did with the help of JMP Statistics Software and resulting in this table:

Table 1. Design of experiments setup prescribed by JMP software for testing Yamamoto Diet factors and responses.

In this experiment, after inputting the diet parameters (factors) that I wanted to examine and the outcomes (responses) that I wanted to measure, I made up the 28 diets specified by JMP and seen in the columns titled Wheat Germ, Casein, Sucrose, Torula Yeast, and Salt Mixture. Telling JMP the ranges of the components (factors) I wanted to test, the amounts in the above table were specified, and it should be noted that each line or row represents one run (for a total of 28 runs).

I then measured the 7 responses (cohesiveness, pH, water activity, diffusion rate, synergism, firmness, and antioxidant capacity) and obtained the values specified in each of the columns in Table 1. This data table reflects a huge amount of information and understanding that we can glean from this inquiry-based approach to understanding diets and other rearing systems components and interactions. I then used this table for a neural network analysis also supported by JMP. After selecting the 5 factors and the 7 responses in this dataset, I started a neural analysis with a Gaussian distribution goal and got the following diagram:

Figure 2. Yamamoto Diet neural network analysis diagram showing inputs (in blue rectangles), the neural nodes (in light green circles), and the outputs (in dark green rectangles). Using the Profiler Analysis in JMP, the following graph set was obtained:

Figure 3. JMP Profile of Neural Analysis of Yamamoto Diet factors and responses. Please note from this figure that at a glance we can evaluate (and understand) how, for example, wheat germ in different concentrations affects cohesiveness, revealing that as wheat germ increases, cohesiveness increases. At the same time, as wheat germ increases, water activity and rate of diffusion both decrease while firmness is substantially increased. We can go through all the parameters (or factors) to see how they affect the physical-chemical responses of the diet. For now, suffice it to say that these tools, design of experiments and neural networking allows us to use data-based analysis of physical and biological responses to manipulation of various rearing factors.

Using DoE and Neural analyses, we can further explore relationships between the various factors in the experiments and their responses using 3D surface plotting as seen in two of many possible examples where we see the dynamics of wheat germ concentrations and casein as they affect diet pH and salt mixture and casein effects on pH.

Figures 4a (pH v. wheat germ v. casein) and 4b (pH v. salt mixture v. casein v). This narrative is getting long, so I will stop for right now and resume the discussion soon.

But just to summarize, I hope that I have sparked some interest in the value of using multiple factor analysis as a DoE exploration, and that I have further stimulated readers to be curious about a neural network type analysis of insect rearing systems components. By way of advertisement, this is also an important part of my approach to my online classes in insect rearing.

In the previous post, I gave examples of what I’m calling “the Doctrine of Insect Rearing from a Rationale Perspective.” I said that I would use as an example of rationale the highly influential work of Dr. Robert Yamamoto where his 1969 paper on a diet and rearing system context for that diet has resulted in thousands of publications and countless insects that were produced from the Yamamoto diet and methods. Here is the diet:

Figure 1 Formulation of Yamamoto 1969 Diet for Manduca sexta.

The Yamamoto 1969 diet formulation; and these are neonates and late 5th instar Manduca sexta on the Yamamoto diet:

Figures 2a (neonate M. sexta larvae) and 2b (5th instar M. sexta larvae) feeding on the Yamamoto Diet.

LACK OF RATIONALE FOR THE YAMAMOTO DIET COMPONENTS: The diet formulation in Figure 1 is a wheat germ based diet ultimately derived from Adkisson et al. 1960 Diet and the Vanderzant et al. 1959 Diet that was the forebear of the Adkisson Diet. While the Yamamoto Diet must be considered a colossal success, the paper describing it does not provide rationale for the various components. This makes the Yamamoto 1969 paper a good example of a paper that tells WHAT to do to make a successful hornworm diet but not WHY or HOW the components succeed as they do. We see the same shortcoming in the diets derived from Vanderzant where use of wheat germ sparked a revolution in rearing Lepidoptera and then countless other insects. It was about seven years before the great Dr. Erma Vanderzant returned to the question of “why is wheat germ such a great ingredient?” when we began to understand the “hidden” or “cryptic” rationale for using wheat germ.

A LITTLE WHEAT GERM RATIONALE: On a first level of rationale, we can say that wheat germ is very nutritious and very palatable (yummy). But this is superficial, and we are well-served to go deeper into the layers of rationale. GOING A LITTLE DEEPER: Wherever wheat germ is used in an insect diet it provides these (and many more features): 1) high protein content (nearly 20% on a dry weight basis); 2) all the essential amino acids; 3) phytosterols that meet the need of insects for a sterol nucleus in their food; 4) rich in polyunsaturated fatty acids (including lots of omega 3’s); 5) lots of B vitamins; 6) lots of tocopherol (vitamin E); 7) all essential minerals in fairly generous amounts; 8) fiber, including beta-glucans which help promote gut mobility; 9) various cryptic (or un-identified) sensory stimuli (chemosensory and textural stimuli).

I will take a break here, but in the next discussion I will take us through a still deeper look at wheat germ and the other major components of the Yamamoto Diet using an AI technique known as neural networking. I will do a little “dissection” of an experiment that I did recently with the major components shown here.

This data table reports the results of an experiment that I generated using JMP statistics’ Design of Experiments. SEE YOU IN THE NEXT POST!

I have been struggling for years to raise the standing and respect for insect rearing and the professionals or experts who devote their lives to development and improvement of insect rearing systems. To increase respect for insect rearing, I have suggested several things that would improve the scientific communities perception of and acceptance of what rearing specialists do. Over the years, in my classes, articles, and books, I have used the term rationale, hoping to establish it as a central doctrine for insect rearing practice. In thinking about the lofty goal of establishing doctrine, I went to AI (through Google) and asked this question and got the following answer: Can we consider rationale as a kind of doctrine?:

AI Response: Yes, rationale can be considered a kind of doctrine, particularly in professional, academic, and legal contexts where it represents a standardized, foundational framework for reasoning, justification, or action. While a rationale is broadly defined as a set of reasons for a decision, it functions as a doctrine when that set of reasons becomes an established, consistent, and accepted framework.

OK, then, having gotten AI’s blessing to call rationale based approach a doctrine, what are the elements or framework of the rearing rationale doctrine?

1. Rearing experiments have a purpose such as rearing insects for food/feed, for research subjects, for insect pest management (including SIT), for biological control, for medical purposes (e.g. medicinal maggots), as pets, etc.
2. Within the context of purpose, we usually rear insects with outcomes such as quality and/or fitness as part of our goal.
3. The rationale should include the general reason(s) behind the overall process AND the rationale for specific components (materials and processes or procedures) that make up the rearing system.
4. While it is of practical value to learn, from our experiments, what to do, it is of greatest scientific value to learn why or how things work as they do. It is helpful to think of the what as the technology of rearing and the why or how as the science of rearing systems.
5. Insect rearing is founded on the rearing system concept where we can think of the rearing system as a kind of artificial ecological niche where we must include all the essential features that the insect requires in its natural environment.
6. The general reasons for rearing a given insect include the purpose mentioned in Item 1 in this list: for example, “in order to do genetic experiments with an insect, it is beneficial to have control over the insect’s environment, genetic history; so rearing the insects under controlled conditions is useful to that purpose.” For the specific rationale, we could be explaining the basis of using live yeast in a diet for Drosophila melanogaster (such as the pioneer rearing and genetics scientists offered in the early 1900s.) To be even more specific and to offer a more informative element of our rearing experiments, we would become more granular in our rationale, observing that yeasts have high protein contents with rich endowments of essential amino acids, or that their content of water soluble vitamins (including the B vitamins), and that the lipid content of the yeasts (generally Saccharomyces cerevisiae) includes sterols and omega 3 fatty acids, and that the beta glucans that are richly endowed in yeasts provide fiber and texture that are beneficial to the insect’s feeding system.

I will end the discussion of rationale as a foundation for doing good scientific research on insect rearing systems; but I will continue this topic soon, with an example of WHATs, WHYs and HOWs in insect rearing where I will focus on a specific paper that helped revolutionize insect rearing: the 1969 paper on rearing tobacco hornworms (Manduca sexta), written by Robert Yamamoto (here at North Carolina State University).

Dr. Robert T. Yamamoto in the 1960s or ’70s.

First, let’s find a definition and characterization of “oracle.” A Google AI search gave us this characterization: “An oracle is a person, shrine, or medium believed to provide wise, prophetic counsel or divine revelations, often associated with ancient Greek figures like the Oracle at Delphi. It also refers to an expert who is an unquestioned authority on a subject.” Well we aren’t looking for shrines, but the rest of the definition applies to what many rearing professionals or staffs seek in getting help on either developing or improving rearing systems.

People in the insect rearing community often need and seek a person or medium that can give them answers to questions such as how do I rear a given insect? How do I solve a problem in my existing rearing program? I am suggesting in this blog entry and the one I posted yesterday that NEURAL NETWORKING (NN) can be a kind of oracle or source of rearing wisdom. It is an AI tool that helps us manage huge amounts of information about rearing systems. It is especially helpful as a way of looking into our own rearing system–especially if we have been diligently building baseline information about our rearing system.

For the current discussion on NN applications, I am exploring the question: “How can I rear painted lady butterflies (Vanessa cardui) on an artificial diet?” I am exploring this question from three possible vantage points or 3 tiers.

Tier 1: Google response to “rearing painted lady butterflies on artificial diet”:

Rearing Painted Lady butterflies on artificial diet is a straightforward process, often done using pre-mixed “cookie dough” or agar-based diets available from educational suppliers like Insect Lore or Carolina Biological. Larvae are kept in cups at room temperature, feeding for 10–14 days before pupating on the lid. Google’s AI synthesis gives us a few useful pieces of information, for example that we can get the diets and the insects from Insect Lore or Carolina Biological (two of several suppliers of these insects and pre-made diets).

Tier 2: The initial summary by Google’s AI tool does not give many rearing details, however, but a further search–if you happen to know that Chen Zha and Allen C. Cohen published a study of Helicoverpa zea and Vanessa cardui in the following:

Research Article – (2014) Volume 3, Issue 1 

Effects of Anti-Fungal Compounds on Feeding Behavior and Nutritional Ecology of Tobacco Budworm and Painted Lady Butterfly Larvae: Entomology, Ornithology & Herpetology:

Chen Zha and Allen C. Cohen^*Program Coordinator & Research Professor, Insect Rearing Education & Research Program, North Carolina State University, USA^*Corresponding Author:Allen C. Cohen, Program Coordinator & Research Professor, Insect Rearing Education & Research Program, North Carolina State University, USA, Tel: 919-513-0576 Email: accohen@ncsu.edu

Zha and Cohen, Entomol Ornithol Herpetol 2014, 3:1DOI: 10.4172/2161-0983.1000120. If you went to the open-access article by Zha and Cohen, you would find granular details about the way the diet is made and other key rearing factors for painted lady butterflies and corn earworms. OR, if you searched a high caliber search system such as Web of Science, using the key words, “painted lady| rearing| artificial diet,” you would find a few papers listed where rearing painted lady butterflies is mentioned, but none of these articles provided details on the diets you would use, only that proprietary diets were purchased from suppliers. So this chase leads us back to our laboratory where we are trying to develop or improve a diet for painted lady butterflies. So far, neither open AI searches nor conventional literature searches have given us much help. Part of this problem is one that I have complained about for years–that even when rearing information does exist somewhere in the literature or the scientific world, it’s too often hidden from easy access. But this is another problem to be discussed in a future blog post. For now, I want to get into Tier 3 using neural networking to help us find ways to improve or establish a diet for a target insect.

Tier 3: For using neural network analysis and predictions, let’s use an example of an experiment done in my lab recently. I used DoE to set up an experimental protocol to determine which of the 5 major components of the Yamamoto 1969 diet for tobacco hornworms. Here is the dataset:

Next, see the diagram for the neural network with its inputs, outputs, and nodes where calculations take place.

Figure 2. Shows the inputs from Yamamoto Diet prepared with different concentrations of wheat germ, casein, sucrose, torula, and salt mixture and further showing the outputs cohesiveness, pH, etc. The prediction profiler shows the initial response of the neural network analysis.

Figure 3. The output of the JMP neural network analysis showing the effects of all factors that are diet components and that were varied in this set of experiments. Note how, for wheat germ for example, the increase in wheat germ decreases the syneresis (which is the “leakage” of water from the gelled diet). At the same time, increasing wheat germ increased the firmness and cohesiveness of the diet–both qualities being desirable for most insects.

We will explore this AI-neural network-based approach in the next blog entry.

Happy rearing!

First, if you like what you see in today’s blog, you are bound to like how I will be teaching this approach to AI-based neural networks and Design of Experiments in my upcoming (May, 2026) Insect Rearing Fundamentals class.

I have been touting the advantages of using design of experiments (DoE) to help us better understand interactions of components in insect rearing systems and to further our grasp of which components are potent forces towards the improvement of our systems. In this blog entry, I am trying to explain how we might start some initial rearing system inquiry using the powerful AI tool neural networks (often called artificial neural networks). I use the JMP statistical package for my DoE and other statistical practices, and I have found the JMP procedures to be very user friendly for people like me who are NOT mathematicians or statisticians. This is especially the case for my learning to apply neural network processes to my rearing inquiries.

For one thing, in my many ventures into websites and other resources that help explain the nature, value and procedures in neural networks, I found a most compelling, entertaining, and clear tutorial from Professor Dmitry Shaltayev (https://youtu.be/u-ngF1YXqhY ). Though his presentation does not use examples from insect rearing, he is very clear and very compelling in his tutorial. First, he starts with the derivation of neural networks from the mammalian nervous system where neurons have dendrites, cell bodies, and axons that receive and process neurological information. He further explains how neural networking/AI is central to facial recognition, self-driving cars, and many other applications. He also uses the JMP software, so his explanations are very useful to me in my JMP neural network adventures.

Secondly, I must mention (by way of a plug for my book: Design, Operation, and Control of Insect Rearing Systems, Cohen. 2021. CRC Press. Boca Raton FL) that I have already made an argument for using neural networks, and my examples here are taken from my discussion.

In this study, I had used design of experiments to set up an experiment with diets for painted lady butterflies, using their weights as the responses and several diet components as the factors (or experimental variables). Here is the data table representing these values:

Next I fed the terms (factors and responses) into a JMP neural network analysis and got this diagram to represent the inquiry;

First, please note the Prediction Profiler (a typical output of JMP analyses) and the little graphs that show, for example, that between agar and gellan as gelling agents, agar use consistently resulted in greater biomass. Also, soy flour showed a slight but consistent tendency to yield higher body weights than wheat germ; brewer’s yeast here seemed slightly better than torula yeast, and casein gave much better results (higher weights) than did whey protein.

Second, I point out that this system of running multiple factors (rather than one factor at a time) is much more useful in understanding interactions of the components and giving us a much more realistic experimental framework where the factors are “dissected out” to show their contributions to the responses.

Third, I caution the readers that this set of experiments is still not definitive. The outcomes may vary according to which species are being explored, which sources of the components are being used (agar varieties differ from supplier to supplier and even from batch to batch).

I will address all this and more in near future blogs. I hope you tune in, and I hope you are encouraged to think about using DoE and neural networks to develop and improve your rearing systems!

Happy Rearing!

This mulberry silk moth (Bombyx mori) is a product of over 5,000 years of domestication and rearing. The domestication of the hundreds of species of insects that we currently rear should be a testimony that rearing is not for dummies. In contrast to the popular trend of simplifying everything from Artificial Intelligence to Vegetarian Cooking (over 300 “For Dummies” titles listed in Amazon), I am going against the grain in touting my writings and teachings (my online and in person classes) as being intellectually based and seeking to give a deep and far-reaching understanding of the complexities of insect rearing.

I hasten to say that I think it’s a clever way to approach topics that would put people off (Economics, Physics, Religious Philosophy, etc.), but without deliberately relegating insect rearing as a “for dummies” concept, the entomological community has done a disservice to the potential of insect rearing to contribute even more than it has to the well-being of humanity.

I have devoted several recent posts and will devote several more to make my point about how the statement attributed to Socrates “The unexamined life is not worth living” applies to the complex practice of insect rearing.

I hope you will examine some of my posts.

==Allen Carson Cohen

I continue here with an explanation of my approaches to insect rearing teaching and research. In my recent posts, I discussed my early efforts to develop a practical artificial diet for predatory insects, mainly Hemiptera/Heteroptera species. I confessed my many failures, disappointments, and frustrations that resulted from my (and the entomology community, in general’s) ignorance about the true feeding habits of the big-eyed bugs and other insects with piercing and sucking mouthparts. In the past few blogs, I mentioned that my realization that the predators were using extra-oral digestion (EOD) and that EOD had far-reaching implications for understanding feeding biology of many species of insects and other arthropods. In fact, right now (February of 2026), I am writing a paper on the discovery of EOD as a feeding “strategy” of the wood-eating buprestid beetle, the emerald ash borer! I also must point out that a fairly recent paper by Ramsey et al. 2019 (with myself as one of the co-authors) clearly documented that Varroa mites, which were long considered hemolymph feeders were indeed feeding on fat body and other semi-solid tissues and NOT hemolymph. They were using EOD to liquify the honeybee’s tissues. Case by case, when we learn in depth the feeding dynamics of many (most?) species of insects, we find that they are doing some sort of pre-oral/extra-oral processing of the food.

What results did we get from recognition and understanding of the true feeding strategy led to development of artificial diets for big-eyed bugs and other species, including green lacewing larvae (Chrysopidae). Despite this clear example of the benefits of “knowing our insects,” too often researchers (like me in my novice insect rearing researcher days) try to accomplish difficult goals without adequate knowledge of their subjects. In my writings and teachings, I try to illustrate the benefits of in depth, mechanistic knowledge of the insects and other rearing system components (diets, environment, microbial relations, containers, hidden interference in our rearing conditions) for success in developing rearing systems and in maintaining working systems. This takes us back to my main point here: exploring how and why, rather than what is the best path to rearing success!

More about HOW and WHY vs. WHAT or Rationale-Based Inquiry

When I write or speak about the efficacy of understanding HOW and WHY, I am getting at the idea that rationale is an all-important part of experimentation. When I would do science demonstrations with my wife’s 5th graders, they always wanted to see what would happen if…. This is a great thing to be curious, but advancing past simple curiosity, we do better (less randomly) if we have a knowledge-based reason for what we experiment with. To test my commitment to this concept, I used a word search in my Insect Diets book and found more than 70 uses of the term rationale, and in the Design, Operation… book, I found more than 100 times that I used rationale to explain how or why a material was used or a process was applied. For example, in both books, I tried to probe deeply into wheat germ to ask why it was so widely useful as a diet component (now for hundreds of species of insects and the production of trillions of insects). But many decades ago, the great Dr. Erma Vanderzant had the same type of curiosity about the wonders of wheat germ.

The excerpt below (Figure 5) shows the first page of a 1967 paper where wheat germ’s qualities are explored by Vanderzant: she explained many of the qualities of wheat germ. Clearly Vanderzant went back to her first use of wheat germ in 1959 considering why the wheat germ did not work well with boll weevils, but why it DID work well with pink boll worms and subsequently with various other insects. She discusses the proteins, lipids, carbohydrates, minerals, and B-vitamins and the other components that “worked” or did not “work” for various insects.

By the way, I had wondered what originally motivated Vanderzant to use wheat germ in her boll weevil and the 1960 (Adkisson et al.) diet for pink bollworms. I had even contacted (some time after her death) a member of her family to ask if he knew what her reasoning was when she first tried wheat germ, and he did not know.

This concludes today’s discussion of the benefits of rationale-based inquiry into the WHY’s and HOW’s of insect diets and other rearing systems components. I will continue this discussion as a basis for my zeal to influence rearing researchers to consider as many facets of their experimental factors as possible. Please watch for more posts to follow soon!

Figure 1 (Feb. 22, 2026 Blog). Euthyrhynchus floridanus (the Florida predatory stink bug) 2nd instar nymphs feeding on a Tenebrio molitor pupa. This colony came from the late Professor William S. Bowers from the University of Arizona. The large size and rather easy rearing of this predatory stink bug allowed us to use it as a model system to study extra-oral digestion (EOD) and other features of its hemipteran/heteropteran biology.

By December of 1983, I had finally learned that the original concept or model of feeding by predators from the sub-order Heteroptera did NOT make their living by sucking liquids (essentially hemolymph) from their prey, but instead, they used EOD to inject digestive enzymes that turned the prey’s internal contents from solid or semi-solid structures like muscles, fat body, etc. into a runny slurry of cellular debris and dissolved nutrients. In my early studies of EOD, I learned the more accurate model of feeding that allow the predators to use much more nutrient rich foods than simple hemolymph. For example, the ingested slurry was at least 5 to 10 times as concentrated with proteins, lipids, and other key nutrients than hemolymph itself.

I will address the various outcomes of using EOD by many, many species of arthropods, but for now let me turn to the practical issue of diet development. If our target predators were ingesting hemolymph, they were getting more than 90-95 mg of water from each 100 mg of ingested hemolymph (leading to hypothesis 1: strictly liquid feeding). However, if the predators were ingesting all (most) of the insides of their prey, they would be consuming about 50 mg of water for every 100 mg of ingested material (slurry). This means that through EOD, they were about 10 X more efficient at extracting solid, high-nutrient food from their prey. Therefore, our second hypothesis was that through EOD, the predators were feeding selectively and more efficiently on high nutrient materials. The affirmation of this 2nd hypothesis led to the “if…then…” conclusion that if we offered the predators non-insect diet components such as meat products, their food would be much more like insect insides in their nutrient concentration, texture/consistency, and digestibility. The experiments with meat diets proved successful after we made adjustments for proportions of various nutrients and a suitable presentation system that would adequately mimic the natural prey, leading to the below publication:

Figure 3 (Feb. 22, 2026 Blog)Showing two Geocoris punctipes feeding on the Cohen 1985 artificial diet made from beef liver, ground beef, and sucrose solution.

Figure 4 (Feb. 22, 2026 Blog) shows two Euthyrhynchus floridanus (predatory stink bugs, family Pentatomidae) feeding on the Cohen 1985 diet developed for G. punctipes (see Figure 3).

Now, let’s see where we are. The diet which I developed by learning how predatory Heteroptera actually feed, using extra-oral digestion, rather than the “drinking straw” concept was so successful that these predators and others such as the predatory stink bugs could feed on it and develop and grow effectively. This leads to the main point of these blog discussions: By knowing the mechanisms of our insects’ biology which we learn through careful observation supported by experimentation, we have much greater power over the systems we are working with.

Once I started to have some successes (among MANY more failures than successes), I became transfixed by the complexities and the rewards of insect rearing, and I devoted the rest of my professional life to discovery of insect biology through science-based inquiry into the insects themselves and the rearing systems we design for the insects. The drama and excitement of this kind of discovery and the applications that come from it are the basis of all my teaching and all the research I have been doing and hope to continue to do.

I’ll explore more of this in blogs on this site. I hope you will join these explanations and the suggestions that I offer in the website and in my courses.

Happy Rearing!