We Rear Insects

I have been a researcher in insect rearing since 1979. During the past 47 years, I have done hands-on research, writing, reviewing, reading, and editing rearing studies and related studies of all aspects of insect rearing. I have had many successes and many more failures in my efforts to develop or improve rearing systems. I have struggled with the entomology community and the infrastructure of rearing, and from my experiences with doing and thinking about rearing EVERY day for these 47 years ~17,000 days for maybe 8 hours a day–yes, I work on weekends, too–or about 135,000 hours of thinking about rearing research!!!, I am beginning to develop a wisdom and understanding of things that work and things that fail to work in our quest to improve the state of insect rearing.

CONFESSION: Though I said I was a rearing researcher for 47 years, I have also been a teacher for over 60 years (starting with high school English teaching which I began in 1965), and above my passion for rearing research, I have an even deeper passion for teaching–sharing whatever I know with everyone who cares to learn from me. Much of what I say here about rearing research is what I’m calling an Inquiry-based approach that has come from my ongoing teaching.

Research and Teaching: Just before I was discharged (honourably) from the US Marine Corps, I was having some dental work done at El Toro Marine Base, and the dentist asked me what I was going to do after my discharge and I proudly told him I was going to become a teacher. His brusque reply was, “Oh, everyone knows if you can DO, you TEACH.” I never forgot this insult, and to this day I attribute by ever-deepening understanding of rearing science to the combination of my teaching with my research.

Doing and Teaching/Teaching and Doing: The more I worked with students of insect rearing, the more I realised how under-supported rearing education was. In my own publications and the thousands of rearing publications in the literature, I saw the same pattern in reports: WHAT works, but little attention to HOW or WHY it works = RATIONALE. Vanderzant’s group (Adkisson et al. 1960) taught us that wheat germ works for pink bollworms (or later for tobacco hornworms and hundreds of other insect species).

Yamamoto 1969 taught us that torula yeast works in the diet for tobacco hornworms, but he never explained how or why it works. These two papers were revolutionary in the doors they opened for insect rearing with artificial diets, so learning what works is super important. But if we can understand how and why wheat germ and torula yeast work as they do, we have amplified power that comes with knowledge to make more likely that we will be able to predict or analyze failures and we have far more power to project how rearing components can be used for other purposes. One of my axioms of insect rearing is DETAILED RATIONALE EMPOWERS US TO INNOVATE. Erma Vanderzant (1967) herself returned to wheat germ to explain much of the characteristics/qualities of wheat germ to help spell out the basis of its value in insect diets. In her 1967 paper, Vanderzant provided a model for how researchers can focus on qualities of a diet component (wheat germ’s quality protein, unsaturated fatty acids, vitamins, etc.) that confer upon a material a deeper understanding of how and why it fits the needs of rearing practitioners.

It is this HOW and WHY that lead to explicit rationale that drives my teaching about insect rearing. My courses are designed to treat extensively the mechanistic, cause and effect thinking that leads to treating insect rearing as a quantitative science, rather than an anecdotal art. I will discuss this topic further in near future blogs.

Tobacco hornworm neonates on Yamamoto Diet (top): the diet formulation as prescribed by Robert Yamamoto 1969. This paper has been cited more than 300 times, and it served as the basis for a paper by Bell and Joachim 1976, cited well over 1,000 times.

Adkisson, P.L., E.S. Vanderzant, D.L. Bull, and W.E. Allison.1960. A wheat germ medium for rearing the pink bollworm. Journal of Economic Entomology. 95: 256-260.

Bell, R.A., and F.G. Joachim. 1976. Techniques for rearing laboratory colonies of tobacco hornworms and pink bollworms. Annals of the Entomological Society of America: 69: 365-373.

Yamamoto, R.T. 1969. Mass rearing of tobacco hornworms II. Larval rearing and pupation. Journal of Economic Entomology. 62: 1427-1431.

Vanderzant, E.S. 1967. Wheat-germ diets for insects: rearing the boll weevil and the salt-marsh caterpillar. Annalsof the Entomological Society of America 60: 1062-1066..

Insect Rearing Fundamentals: May, 2026

This is a compressed version of the course syllabus. Please note that each day’s class meeting is 3 hours long, including a 5 minute break at the halfway point. I make frequent stops to ask for questions or other student/participant input. The course is designed to include materials from my books, Insect Diets: Science and Technology 2nd Edition 2015 AND Design, Operation, and Control of Insect Rearing Systems 2021, both from CRC Press. The live, real-time classes go beyond some aspects of the books where 1) materials are constantly updated as I become aware of new information, including my own original research and my activities as an Academic Editor of the MDPI journal, Insects.

As with recent offerings of the Fundamentals course, the registration fee is $450 (US$), and the information for registration is specified below in a previous blog page.

As always, I invite specific questions about the course through contact with me at this email address: accohen@ncsu.edu

In May of 2026, Allen Carson Cohen will be teaching an online insect rearing fundamentals course. The course is 24 hours of instruction via Zoom with lots of interaction between participants (students) and Professor Cohen. We have updated this course to include new information about rearing systems, their standard operating procedures, using statistically-based optimization, engineering of the rearing systems, and up-to-date technology for measuring quality and process control. While getting into new approaches, the course also contains standard information that has been covered conventionally in these courses and in Professor Cohen’s books and recent papers.

Here is an example from Allen Cohen’s recent research on interactions of components in diets, using a JMP statistical system’s format for diet texture using the 1969 Yamamoto Diet for tobacco hornworms (Manduca sexta).

In this figure, we can see an example of the kinds of exploration we can do with a design of experiments (DoE)-based inquiry. In the experiment illustrated here, we were asking the question: how do components of the Yamamoto (wheat germ and yeast) diet interact to give the diet varying degrees of gel firmness. This type of approach allows us to understand not just WHAT works in our diets, but more importantly HOW or WHY it works (or fails to work).

In this class and in all Professor Cohen’s classes, we strive to learn the mechanisms, rationale, and basic science behind our rearing systems’ components. We strive to learn HOW and WHY things work as they do in terms of the biology of the insects in our systems, the physical and chemical nature of the interactions of rearing systems’ components, and in knowing the HOWs and WHYs, we are better able to engineer our systems and generate standard operating procedures (SOPs) that are data-based and well-vetted.

If this approach sounds interesting to you, please see the next Blog Page for details on course contents and registration details for the May 2026 class.

Why Use Design of Experiments (DoE or DOE)?

Instead of studying one factor at a time, rearing specialists can inquire about how multiple factors (or experimental variables) function within an insect rearing system. By doing DOE procedures, we can save on costly runs for our experiments; AND we can discover interactions between factors that we could not understand by using one-factor-at-a-time (OFAT) experiments.

Some History of DOE in Engineering and Science and Specifically in Insect Rearing Science:

After struggling for almost 25 years (1979-2003) to develop artificial diets for various insects, I wrote the book Insect Diets: Science and Technology in 2003 (CRC Press, Boca Raton, FL) where I had stated that insect diet experts were burdened with experimenting with one factor at a time in their need to conform to “proper” experiemental design, which demanded a single factor or variable that was responsible for an outcome/effect/response.

Soon after my pronouncement about one factor at a time experiments, Dr. Steve Lapointe and his associates published a paper that was revolutionary for me and in my opinion for the entire community of insect rearing specialists: (Lapointe et al. 2008) where Lapointe and his team stated the reality that insect diets were mixtures and as mixtures could be treated with the statistical frameworks that described and helped analysis of complex mixtures and combinations of other interacting factors. Frankly, when I read Lapointe’s bold assertion that things could be done much more parsimoniously and effectively with multiple factor experiments, I was hurt and embarassed that my seemingly authoratative pronouncement was incorrect and naïve (though the authors were gentle with my assertion, I still felt a sting from having my authority challenged). After “licking the wounds of my pride,” I started to ask what was Lapointe talking about—doing experiments with multiple factors—using several variables in one set of experiments?

Reference: Lapointe, S. L., Evens, T. J. & Niedz, R. P. Insect diets as mixtures: Optimization for a polyphagous weevil. J. Ins. Physiol. 54,1157–1167 (2008).

In this historically important paper, Lapointe et al. used a response surface design to test multiple factors to improve a diet for Diaprepes a weevil that had proved difficult in prior efforts at diet development/improvement. The group showed that using the response surface design greatly simplified diet development, but beyond the importance of the accomplishment for a single insect the Lapointe group showed that DOE was a most valuable tool in diet development and for that matter rearing system development and improvement in general.

This set me into motion to try to learn how DOE worked and how I could apply it to my rearing/diet development goals. I will tell that story and my walk through the DOE system that I have been using: the JMP statistical package. Please see the following blog pages in the next few days….

Reminder: Professor Allen Carson Cohen will be teaching a live, virtual course, using Zoom, starting June 3, 2025 through July 10, 2025. Classes will go from 10:00 am (1000 hours) through 12:00 noon (1200 hours) each Tuesday and Thursday. Registration cost will be $450, and classes are taught as continuing education courses through the North Carolina State University’ Office of Continuing Education and Professional Development.

To register for the class or to get more information, please use this link: https://lifelonglearning.ncsu.edu/reporter_course/insect-rearing-system-fundamentals/

Also, for further information about registering or other course matters, please contact Mr. Jamie Merritt, Program Coordinator at this email address: jpmerri2@ncsu.edu or Ms. Darthea Powden at this email address: dpowden@ncsu.edu

For any further information about the course contents and issues regarding your expectations, please feel free to contact Professor Allen Carson Cohen: accohen@ncsu.edu

This diagram represents several features to be covered in the upcoming course.

Classes are taught as live lectures and discussions with participants encouraged to interact with Professor Cohen. The live presentations allow interactions between participants and with materials that include PowerPoints, videos, demonstrations, and many resource materials presented through the highly-touted Moodle system.

Please check the next blog page for May 15-16 on using design of experiments as a basis for developing and improving rearing systems.

To view the video in this tutorial example, please right click the image and select “Show Controls,” then click the forward arrow to view the video.

The special feature of this approach is that collaborators or teacher/learners can communicate live through Zoom or other remote formats and share ideas, explanations, etc.

This is an example of a tutorial where the collaborators (Professor Cohen and Dr. Carole Cheah) were exchanging information about diet development for their project dedicated to development of artificial diets for predators that are specialists of hemlock woolly adelgids. In this video, recorded from a video collaboration, Drs. Cheah and Cohen review various aspects of the acceptance of the artificial prey (artificial diet later published in a 2015 paper (published here: Cohen and Cheah, Entomol Ornithol Herpetol 2015, 4:2 http://dx.doi.org/10.4172/2161-098)

The main point of this blog page is to illustrate the potential quality and efficiency of remote communication (Cheah was in Connecticut and Cohen was in North Carolina for this Zoom meeting). Note that the video here includes only Dr. Cheah’s part of the communication where Cheah showed Cohen videos and still shots of the beetles she was feeding diets produced by Cohen as freeze dried samples of their “CC Diet.” Dr. Cheah was testing the responses of the beetles to the diets with various additives and diet presentation conditions such as on or off of hemlock foliage or Parafilm or other substrates. Please note further that Dr. Cheah at the time was using a simple phone-camera and shot the videos and stills through a dissecting scope eyepiece.

This type of exchange works well for many other kinds of information exchanges which can be done live and which can further be made to include multiple research or rearing education partners.

Cohen is currently offering this type of collaboration and teaching as part of an online experience for collaborators or participants worldwide.

MORE TO FOLLOW SOON!

This post and several others to follow are intended to narrate how I approach teaching about insect rearing systems and how I approach developing and improving these systems. I am writing this page on February 14, 2025 almost 50 years after I started out in insect rearing at the University of Arizona and the USDA, Agricultural Research Service in August of 1979. During this time, I have had several successes and several failures at developing and/or improving rearing systems. It has become the focus of my life to better understand why systems and the components of those systems work or fail. These pages are my effort to explain what I have learned in trying to understand the scientific principles behind rearing.

First, the concept of the rearing system as an ecological niche: before I was an entomologist/rearing specialist, I was an ecologist. Over the years, I have come to appreciate the reality that as rearing specialists, we are obligated to provide all the components that our insects would have in nature–only we must put them all into our rearing system. THIS IS TO SAY THAT OUR REARING SYSTEMS ARE ARTIFICIAL ECOLOGICAL NICHES!

As “NICHE-KEEPERS,” we must provide the food, the gas exchange, the heat, light, humidity, sites for oviposition, microbial relations, mating sites, oviposition sites, etc., etc. Are we giving our insects the right conditions to safely void their urine and fecal wastes? You watch a leaf-eating caterpillar in nature dropping its frass from the leaf-feeding site to the ground. How must they release their wastes in our containers? We know what is convenient for us as the rearing personnel, but is that what is best for the insects?

The two pictures in this post show a little of what I mean by factors in the ecological niche concept of insect rearing systems. The top picture is an attempt for me to show in multiple dimensions (based on G. Evelyn Hutchinson’s “N-Dimensional Hypervolume” as the model of an ecological niche). The idea here is that CO2 generation and O2 uptake are not only related to one-another, but they relate to the thermal conditions and the food the insect is eating. The ratio of CO2/O2 or the respiratory quotient are indicators of whether the insect is metabolising mainly carbohydrates, lipids, or proteins. If being a little confusing with all this and other factors seen in the top diagram, it’s what I intend to do to convince you that this is all pretty complex and VERY INTER-RELATED stuff.

The second picture showing the diet (developed by R.T. Yamamoto 1969) for Manduca sexta is also a complex of components such as wheat germ, casein protein, torula yeast, vitamins, and minerals that are all interacting with one-another to give the diet a composition, texture, consistency, and configuration that help determine the success of our tobacco hornworm rearing system. One reason that the diet is (in my opinion) so successful for M. sexta is that it provides lipids (fatty acids and sterols, for example) in the form of lipoproteins which make these essential lipids bioavailable for the larvae. One of the wonderful features of wheat germ is that it contains nutritious proteins with all the essential amino acids, but also some of these proteins are lipoproteins, which carry the lipids in a bioavailable way compatible with our hornworms’ digestive system.

More along this line in my next blog entry. Happy Valentine’s Day!