Rearing and Eating Mealworms

Target Audience

 

Estimated Time for Lesson

 

Overview of Lesson

This is a two part lesson on rearing mealworms (Tenebrio molitor)(Figure1). In Part 1, students will learn about insect basics. This portion has students explore what they already know about insects, learn about the insect’s life cycle, and have hands on experiences with different life stages of an insect. Part 2 has students conduct a feeding experiment with mealworms. Students can hypothesize what foods will influence insect taste. They are also asked to record their observations over time via social media accounts. This lesson is good for students who may not have any prior experience with insects in a learning environment.

 

 

Figure 1. Photo of T. molitor. Moving left to right the larva, pupa, and adult.

 

 

Background and Introduction to the Study Insect

Mealworm is a common name given to many members of the Tenebrio genus. The species we will be working with is Tenebrio molitor, commonly known as darkling beetles. They undergo complete metamorphosis, and live in temperate regions. They often feed on grains and decaying matter. You can often find them hiding underneath logs or burrowed in grains. The larval stage is commonly referred to as a “mealworm,” and can be consumed by humans. This insect was selected for this lesson because it is easy to access, easy to care for, poses no threat to the classroom, and is commonly consumed by humans.

Learning Objectives

Next Generation Science Standards

HS-LS2-7: Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity

Within this lesson, students should learn about the impacts of human activities on the environment and biodiversity, learn about how entomophagy can be a potential solution for reducing human impacts, and explore one factor in the implementation of entomophagy in Western Nations.

HS-LS2-8: Evaluate evidence for the role of group behavior on individual and species’ chances to survive and reproduce

Students will learn about the population dynamics regarding the raising of darkling beetles (Tenebrio molitor). Additionally, students should develop an understanding of the different factors that will play a role in the population of darkling beetles.

Teacher Lesson Plan Instructions

Insects are consumed as food sources across the globe. However, they are often not consumed in many Western Nations. Some argue that insects should be used more often in Western nations as a way to curb Greenhouse Gas emissions and be more sustainable with our food consumption. In 2013, the Food and Agriculture Organization of the United Nations began encouraging Western nations such as the United States, the United Kingdom, and Canada to begin utilizing edible insects (Van Huis et al., 2013). As such, there has been research looking at how disgust towards insects plays a role in why Western Nations do not use insects, the role of insects in developing nations, and how Western Nations can better utilize insects.

Insect farms, places that rear insects for human use, hypothesize that insect diet will influence insect taste. While there is plenty of anecdotal evidence to support this hypothesis, there is little scientific literature regarding this topic. The idea behind insect taste is that insects will take on the taste of whatever food they are fed due to their small size. Mealworms often feed on cereal, oatmeal, bran, and old vegetables. Potential differences in the types of vegetables fed to mealworms may result in differences in mealworm taste. The goal of this activity is to introduce students to the idea of edible insects and conduct an experiment regarding insect taste.

Activity

Part 1: Introduction to Insects

Prior to starting this lesson you should purchase mealworms and tank accessories for the classroom. Set up two cages if possible. Purchase information and set up instructions under Teacher Notes.

Suggested Reading for Students to Complete Prior to Class:

https://blogs.scientificamerican.com/observations/mealworms-the-other-other-other-white-meat/ – About the use of Edible Insects

Biology Guide and Observation Kit (Fluker’s Farm) – Mealworm care; Read: Introduction, Overview of Growth and Development

http://www.sialis.org/raisingmealworms.htm – Mealworm Care

https://drive.google.com/drive/u/0/folders/0B46WJt5cWLFoM3ZFbFFMVUhZWDA?ths=true – Some research about the influence of feed on insect taste; Article Title: A Descriptive Sensory Analysis of Honeybee Drone Brood from Denmark and Norway

https://www.youtube.com/watch?v=tq52cQ4R_20&t=440s – Youtube video on Mealworm habitat

Have students pull out a piece of paper and write down at least three things they already know about insects and three questions they have about insects. Then, discuss as a class what they already know; write down ideas on the board for the whole class to see. As a class, try to answer any questions students have about insects. Invite students to conduct their own research regarding any unanswered questions and report back to the class with what they find.

Use powerpoint (you can use http://bit.ly/2NrA9Az or you can create your own) to talk about insect basics, life cycles, and edible insects. Topics to be covered:

What defines an insect?

The types of insect life cycles and examples

Why do people eat insects?

Benefits of edible insects

Description of activity

Raising and caring for mealworms

Have students find examples of the darkling beetle (Tenebrio molitor) life cycle in the cage (show egg, larvae, pupae and adult beetle).

If possible, place the cages on a desk so students can look into the cages. Have students try to find examples of each life cycle stage within the cages. It may be difficult for students to find eggs, but they should be able to find beetle larvae, pupae and adults.

Have students use powerpoint to confirm they found the correct life stages

Discuss raising mealworms and the experiment activity with students (included in powerpoint)

After discussing the care requirements and experiment with the class, create a student care schedule (example in Appendix).

For the experiment in Part 2, have students select two types of vegetables to feed the mealworms. Would they want to try carrots? Potatoes? Cabbage? You may want to provide three vegetables for students to choose from to prevent students from choosing obscure/more expensive vegetables. These two vegetables are what they will feed the mealworms for the duration of the activity. Recommended: carrots and potatoes. The two types of vegetables will be referred to as “vegetable A” and “vegetable B” from now on in this document.

Assessment: students should create a social media account documenting the growth of the mealworms. This can be done over Instagram, Facebook, blogging, etc. Students should NOT link this to their personal social media accounts. They should update these accounts 2-3 times a week regarding the status of the mealworms. For this social media account, students can state their hypothesis as to whether they think the vegetable will influence the taste of the mealworms!

Part 2: Experiment

Question: Does the food fed to mealworms impact their taste?Hypothesis: Mealworms will taste similar to the food that they are fed. (Example: mealworms fed carrots will taste like carrots.)Warning: Some people with shellfish allergies may also be allergic to insects. Please use the proper food allergen avoidanceprocedures outlined in your organization. Alternatively, you can create a panel of adults (e.g. teachers without shellfish allergies) to do the taste testing, and allow students to interview the testers to determine what they think the mealworms taste like.StepsOnce Part 1 is completed:

1. Once students have had the chance to observe the development of one mealworm life cycle (purchased mealworm stage to mealworm stage) have students collect mealworms from the cages. Put them in the freezer overnight. Development will take at least four weeks.
2. Make sure that mealworms fed vegetable A and vegetable B are kept separate.
3. Dry roast mealworms. This process can be done by yourself, or students can help. Students may be able to start the cooking process in class, and then you can finish the cooking. Or students can come in after school to help dry roast. Mealworms fed vegetable A and vegetable B should be cooked separately.
4. Label the two different batches A and B. Have students try 1-2 mealworms per each food type. Students should record whether they detect flavors of the food fed to the mealworm, and whether they detect a difference in taste (Can record in Insect Taste Test worksheet).
5. Reveal which mealworms were fed which vegetable to students. Record on the board whether students were able to taste the vegetables on the board. This can be done in Excel and then you can easily make a bar graph depicting how many students thought the mealworms tasted like vegetable A, vegetable B, or did not taste like the vegetable they were fed. Or you can just record the numbers on the board for students to see (for example: 17 students thought the mealworms tasted like carrots, 3 did not.)
6. Discuss as a class whether, overall, the vegetable fed influenced mealworm taste. Have students hypothesize why feed may or may not influence the taste of insects.
7. Ask students why or why not it is important to understand what influences the taste of insects. Will it play a role in utilizing edible insects in the future? Are there other factors that may impact our ability to use insects in the future? Do you think this experiment would be different with different vegetables? Record student answers on the board, and use student answers to drive a class discussion.

Teacher Notes

Obtain mealworms as early as possible. You can often purchase mealworms from regular pet stores (such as PetSmart or PetCo) or online (http://www.rainbowmealworms.net/shop-mealworms/). Purchase regular mealworms, some stores will market “mini” or “large” mealworms. While you can purchase these, regular mealworms will work just fine.

A local entomologist may be able to help guide you on purchasing mealworms and setting up their habitat.Students who are allergic to shellfish should NOT eat insects due to potential reactions to chitin.

This lesson can easily be adopted for younger students. Younger students may require more guided inquiry regarding the experiment.

Mealworm CareMealworms can be kept in any sort of plastic or glass terrarium. Cover the bottom of the terrarium with 1-2 inches of grain, for example, oatmeal. Mealworms will primarily feed on the grain. You can also place any decaying fruits or vegetables inside the terrarium to supplement their feeding. Fruits and vegetables will provide adequate amounts of water for the mealworms. Do not place extra sources of water in the terrarium.Once you have set up mealworms, you can continuously rear them. You may want to introduce some new mealworms every year to prevent death due to inbreeding. If you decide to use this lesson every year, then you can simply begin feeding the mealworms the vegetables you are testing at the beginning of the school year to ensure they have only been fed that vegetable. Mealworms develop best in temperatures of at least 75 degrees Fahrenheit. If you wish to slow their development, you can keep them in a cooler room. If you wish to speed up their development, you can keep them in a hotter room.

The Mealworm life cycle is as follows: The female beetle lays hundreds of eggs. These eggs will take about one week to hatch into larvae.Larvae will then burrow below the surface, eat vast amounts of food, and will molt 10-20 times. They spend about 10 weeks in this stage.Larvae will then come to the surface and enter the pupal stage. Pupae will not move or feed very often. They spend 1-3 weeks in this stage. They will then change into beetles. Adults live for 1-3 months.

Mealworm Cooking You may prefer to cook mealworms yourself, or have some students come in after school to help bake.Insects can be cooked in any regular oven. Depending on when you are cooking insects (during school versus after school), you may be able to use ovens that are found in a Home Economics or Cooking classroom. Additionally, you may be able to use ovens in the school’s kitchen after school for cooking.L earning Assessment Example:Insect Social Media AccountReflection Paper

Grading Rubric for Social Media Assignment

The Social Media Accounts must include:

Regular posts 2-3 times a week for the entire development of the mealworms

Social Media accounts should be strictly used for this project (ie: not linked to another account and/or not posting about something unrelated to this project on the account.)

Students should post their hypothesis regarding whether feed will influence mealworm taste

Students should document the progression of mealworm development, interesting things they note about behavior, and other observations regarding the mealworms on their account

The goal of this assignment is to engage students in the rearing of insects over time in a fun way. This rubric may need to be modified based on what type of social media account a student uses. This is written with an Instagram, Facebook, or Bloggeraccount in mind.

An example Instagram can be found at the handle: mealworms

Insects Reflection Paper

Write a 2-3 page paper reflecting on this process of rearing and consuming mealworms. Is it important to understand what influences the taste of edible insects? How would you do this project differently in the future? Do you think this is a practice that could be implemented widely? Is this something you would consider doing? What do you think of others who consume insects? What other questions do you have in regards to insects?

Insects Reflection Paper Grading

Insects paper should be graded on the following:

Completion and thoughtfulness of answers

Student discusses what they have learned over the course of this project

Student reflects on what they have learned over the course of this project

Student develops questions for potential future inquiry

References

Any of these could also be used as suggested readings for students

Fluker’s Farm. Mealworm care sheet. 2018.

https://flukerfarms.com/reptile-u/care-sheets/mealworm-care-sheet

Howcast. How to make a mealworm habitat|Science projects. 2013.

https://www.youtube.com/watch?v=9_PohYVrHFo

Mealwormcare.org. Mealworms. 2018. http://mealwormcare.org/

Smith, E.Z. Raising mealworms: everything you ever wanted to know and more.

2016. http://www.sialis.org/raisingmealworms.htm

Van Huis, A., Van Itterbeeck, J., Klunder, H., Mertens, E., Halloran, A., Muir, G., and Vantomme, P. 2013. Edible Insects: future prospects for food and feed security.