Mealworm: All You Need to Know for a Sustainable Food Choice

Mealworms have gained attention in recent years for their potential as a sustainable protein source and their ability to break down certain plastics. These insects are the larval form of the mealworm beetle and can be found in many parts of the world. They are increasingly being explored as an alternative source of protein due to their low environmental footprint and high nutritional value.

Raising mealworms at home or on a farm can be a simple and cost-effective process. They can be grown in stacked-drawer systems using different substrates, such as wheat bran, oats, or cornmeal. Mealworms also require a source of moisture and nutrients, which can be provided by adding slices of raw potato to their environment weekly. This easy-to-maintain system allows mealworms to thrive and produce a sustainable source of protein for human consumption or animal feed.

Additionally, mealworms have shown promise as a solution to plastic waste. Researchers at Stanford University found that these insects can safely consume certain types of plastic, including those that contain toxic additives, without any adverse effects. This discovery highlights the potential of mealworms to assist in addressing environmental pollution as well as providing a nutritious protein option for the future.

Mealworm Basics

Life Cycle

Mealworms go through four life stages: egg, larva, pupa, and adult.

  • Eggs are white, bean-shaped, and around 1/120 inches long.
  • Larvae, also called mealworms, molt 9-20 times before reaching the pupal stage. They are initially white and darken to a shiny honey-yellow color after shedding their skin.
  • Pupae transform into adult beetles during metamorphosis.
  • Adult beetles, also known as darkling beetles, are nocturnal and black, with a hard shell and about an inch long U.OSU.

Darkling Beetle

Darkling beetles (Tenebrio molitor) are the adult stage of mealworms. They are:

  • Nocturnal insects commonly found in moist, dark, and undisturbed areas.
  • One inch long, with hard shells and black coloring hortnews.extension.iastate.edu

Tenebrio Molitor

Tenebrio molitor is the scientific name for mealworms, which includes all life stages from egg to adult. They:

  • Are potential sustainable food sources for humans.
  • Have low environmental impact.

Nutrition comparison of mealworm powder with sirloin beef:

Food Item Protein (%) Iron (mg) Environmental Factors
Mealworm Powder 55 Higher than sirloin 2,000 fewer gallons of water; less than 20% land use
Sirloin Beef Average 28-35 Lower than mealworm Requires more water and land

Anatomy

Mealworm anatomy includes features found in a typical insect. Some key structures are:

  • Exoskeleton: A rigid, protective outer covering made of chitin.
  • Segmented body: Divided into three main parts (head, thorax, and abdomen).
  • Six legs: Attached to the thorax.
  • Two antennae: Located on the head and used for touch and smell.

Nutritional Value and Uses

Protein Content

Mealworms are a great source of protein, containing about 55% protein in their powdered form. They also provide essential amino acids and fatty acids, making them an excellent nutritional option for various applications.

Feeder Insects

  • Reptiles: Mealworms are commonly used as a food source for pet reptiles, providing necessary nutrients for healthy growth.
  • Birds: They are also used for feeding pet birds like parrots and finches, supplying essential nutrients such as calcium.

Fish and Bird Food

Mealworms are frequently used as an ingredient in fish and bird food, offering a sustainable and nutritious component in their diets. Their high nutritional value makes them particularly suitable for growing and breeding birds or fish.

Fishing Bait

Anglers often rely on mealworms as fishing bait, because their wriggling motion attracts the attention of various fish species. They’re easy to find, affordable, and environmentally friendly compared to other bait options.

Human Consumption

Mealworms can be consumed in various forms, for example:

  • Powdered: The powder can be added to baked goods, smoothies, or protein bars.
  • Whole: Whole mealworms can be roasted or fried and consumed as a snack.

Comparison Table: Mealworm vs Beef

Food Source Protein Content Land Use Water Use
Mealworm 55% <20% 2,000 gallons less
Beef 26% 100% 2,000 gallons more

Mealworms are an environmentally friendly alternative to traditional protein sources such as beef, requiring significantly less water and land to produce the same quantity of edible protein.

Rearing Mealworms at Home

Housing and Environment

To rear mealworms at home, you’ll need a suitable container as their habitat. An ideal choice is a plastic or glass aquarium, with a ventilated lid. The container should:

  • Have smooth sides to prevent escape
  • Provide enough space for the mealworms to grow

For bedding, you can use a mixture of wheat bran, oatmeal, or cornmeal. Ensure that the bedding is:

  • 2-3 inches deep
  • Kept dry to prevent mold and mites
  • Changed regularly to maintain cleanliness

Food and Diet

Mealworms are voracious eaters and will primarily consume their bedding. Additionally, provide fresh vegetables like:

  • Carrots
  • Potatoes
  • Greens

These vegetables help to:

  • Maintain moisture in the habitat
  • Provide essential nutrients for mealworm growth

Temperature and Humidity Conditions

The ideal temperature for mealworms is between 75-85°F. At this temperature, they:

  • Grow rapidly
  • Complete metamorphosis sooner

Proper humidity is essential for successful molting. Maintain a humidity level of 60-70% by:

  • Adding a shallow water dish with a sponge
  • Spritzing water on the bedding

Breeding and Lifecycle Management

Manage the lifecycle of mealworms by understanding their stages of development: egg, larva, pupa, and adult beetle. Control their breeding by:

  • Separating pupae from larvae
  • Transfer adult beetles to a new container for egg-laying
  • Regularly harvesting mealworms for feed

Keep in mind that the larval stage is when mealworms are typically bred and harvested for feed.

Potential Risks and Precautions

Health Risks for Humans and Animals

  • Bacteria: Mealworms can harbor pathogens, so proper handling is essential to prevent contamination.

  • Allergies: Some people may be allergic to mealworms or their byproducts^[1^].

Environmental Impacts

  • Nitrogen waste: Mealworms produce a significant amount of nitrogen waste, which can contribute to pollution if not managed properly^[2^].

  • Plastic digestion: While mealworms can consume and break down plastic, there is still debate over how much of the plastic is truly biodegradable and what environmental effects their consumption may have^[3^].

Controlling Pests and Mites

  • Darkling beetles & mealworm beetles: Adult beetles can infest stored products and may require insecticides to control them in some situations^[4^].

  • Mites: Mites can infest mealworm colonies, negatively affecting the health of the insects. Regular cleaning and proper ventilation can help prevent mite infestations^[5^].

Comparison table of pest and mite control methods

Method Pros Cons
Insecticides Can be effective in controlling adult beetles May be harmful to the environment and insects’ health; requires specific products and proper application
Cleaning and Ventilation Non-toxic and environmentally friendly More labor-intensive; may not fully prevent mite infestations

Utilizing Mealworm Byproducts

Mealworm Castings for Plants

Mealworms produce nutrient-rich castings that can be used as a fertilizer, enhancing plant growth:

  • Castings promote rich soil structure.
  • Include nutrients like nitrogen, phosphorous, and potassium.

These castings work well for both indoor plants and gardens, acting as a substitute for traditional fertilizers.

Fertilizer from Mealworm Waste

Mealworm waste, referred to as frass, is another byproduct suitable for fertilizer. Benefits of using frass include:

  • Boosts plant immunity: Strengthen plants against diseases and pests.
  • Natural source: Less need for synthetic chemical fertilizers.

Here’s a comparison of mealworm waste and traditional fertilizers:

Fertilizer type Pros Cons
Mealworm waste Natural, improves plant immunity, rich in nutrients Less readily available than synthetic fertilizers
Traditional fertilizer Widely available, rapid nutrient release Synthetic chemicals, potential environmental harm

Mealworm Composting

Mealworms can also contribute to efficient decomposition of organic matter. They help in breaking down waste through a process called vermicomposting.

Characteristics of mealworm composting include:

  • Effective: Mealworms can consume a variety of materials, including plastics.
  • Low-maintenance: Easier to handle compared to other composting methods.

In conclusion, mealworm byproducts are versatile and eco-friendly options for plant growth, fertilization, and waste management.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Mealworm Beetle

 

Need This Bug Identified, Please
Location: Western New York State
July 8, 2011 7:02 am
Hi! I’m glad I stumbled upon your site. I’m having a problem this year with these particular bugs (beetles, perhaps?) in my home. Once, wandering around in the bathtub and three times scooting around on the kitchen floor. I’ve never seen these before, well, at least not IN my house! What exactly am I dealing with here?
Signature: Betty

Yellow Mealworm Beetle

Hi Betty,
Check the pantry.  This looks like an adult Yellow Mealworm beetle,
Tenebrio molitor.  The larvae are often sold in pet stores as live food for lizards and other small carnivorous pets.  The larvae will also infest stored foods like cereals and grains.  There may be a box of long expired food on the back shelf in the pantry that is hosting a thriving Mealworm population.  Not eating your oatmeal fast enough?  You can verify this identification on BugGuide.

Letter 2 – Superworm, not Giant Mealworm

 

what is this? Can you tell us about our adopted caterpillar, Pretty Legs? What is she? What does she eat? We found her in our house. Her front legs hurt when she crawls on you. My homeschooled 6 year old daughter is very curious about her. How soon should we release her? Thanks for you help!
Julie

Hi Julie,
We knew this was not a caterpillar, and most probably some type of beetle larva, but we checked in with Eric Eaton for more clarification. Here is his opinion: “The larva here looks like a giant mealworm, Zophobas spp, but I could be wrong. Most likely something in the Tenebrionidae.” So, chances are some stored grain product has some of your visitors siblings munching away. Here is a site on Raising Your Own Insects that will provide additional information.

Update (07/02/2007) Correcting an entry for Giant Mealworm
I wanted to let you know that it is not a Giant Mealworm (Tenebrio molitor) but actually a Superworm (Zophobas morio). I feed them to my bearded dragon every day! You can tell because they have a dark tail and head whereas Mealworms (regular and giant) are fairly uniform in color. This also explains why the woman said it hurt when the worm crawled on her! http://en.wikipedia.org/wiki /Superworm
http://www.superwormfarm.com /page3.htm
Naomi

Letter 3 – Mealworm

 

what is this horrible looking thing???
Hello, great site you have here. Been browsing it for a bit but still cant find this little chap on there! Found him under my carpet, with the cat sniffing near it. Don’t know if it came in off the cat, or if there is something in the house… It was found near my fireplace, which is not used and has a gas fire in front of it. The chimney is boarded up, but not sealed. Thanks for your help! I’m in the UK, by the way.
Ian

Hello again,
As well as asking you, I also asked the Natural History Museum insect dept. for some help, and they have sent a reply. Just though I would let you know, so you don’t waste any more time on this enquiry! It is a the larvae from a mealworm beetle apparently, and can be found in roofs/attics/chimneys where birds nest. hence why I found it in near my fireplace! Thanks anyway, and keep up the good work on a fantastic site! best regards,
Ian

Hi Ian,
Thank you for your photo as well as the results of your inquiries. During normal business hours, we at What’s That Bug? are in the real world trying to make a living and normally answer questions early in the morning or late at night. We were unaware that the Giant Mealworm Larva, a Darkling Beetle in the genus Zophobas, were found in association with bird nests. It is very interesting.

Correction (03/28/2008)
I just wanted to point out that as Ian was told by the Natural History Museum, this is a Mealworm (Tenebrio molitor) which is not the same as a Superworm (Zophobas morio). Superworms are often confused with Giant Mealworms (the latter being a hormonally enhanced mealworm which grows larger for use as a feeder). While mealworms and superworms are both types of darkling beetles, they do have different appearances.

Letter 4 – Mealworm

 

Okay, I’m a little more calm now…
Dear WTB:
Long time reader, second time e-mailer… firstly, thank you so much for your wonderful website! It is an excellent educational tool and an essential public service! Thanks to you, my daughter is growing up to appreciate and love bugs (with the exception of wasps and hornets — she was bit twice last year) and, thus far, is not acquiring my neurotic hang-ups.
Please find attached pictures of a bug that I found this morning. He was kicking on his back in my darkened kitchen. I am not responsible for the damage to his one antennae and to a couple of his legs. This maiming was doubtless the work of my tiny perfect carnivore (domestic tabby cat). While on his back, I feared that he was an oriental cochroach. Having covered him with a translucent plastic container, I was able to slip a sheet of construction paper under him and tape the container down onto the paper, thus securing him for further observation and study. I spent a couple of hours on your website researching him and was quite convinced that he was an oriental cochroach until we managed to flip him over. Now, I’m pretty sure that he is a harmless species of ground beetle. He is 1.5 cm. long and .5 cm wide (5/8 " long, 3/8 " wide). He appears reddish-brown on his underside and black on his back. I can’t tell you how much I would appreciate it if you would view the pictures and confirm whether he is a beetle or a roach.
Sincerely,
Neurotic, fussy, home-maker (knowing it is half the battle)
near Toronto, Canada

Dear Neurotic, fussy home-maker,
Based on your self-evaluation, we are pretty certain we know what you will be doing the minute you get this response. We are relatively certain this is a Mealworm, Tenebrio molitor. We located a website with the following information: “Tenebrio beetles are black or dark brown and they feed as larvae and adults on grain products. T. molitor is an important post-harvest pest and occurs spread all over the world. Adult beetles are attracted to night-lights, are strong fliers, and are found in dark places. Each female lays about 275-600 eggs, which hatch into larvae in 4 to 14 days. Eggs are laid singly or in clusters during the spring over a period of 22 to 137 days. Larvae firstly eat the germs of stored grains and can feed on a wide variety of plant products such as ground grains, flour, tobacco and foodstuffs. Larvae are very voracious and highly resistant to low temperature; they can remain alive for 80 days at -5

Letter 5 – Mealworm Beetle

 

Legless lizard
November 30, 2010
Hi Daniel.
Haven’t seen a legless lizard lately, but came across a (perhaps) interesting science experiment.  My nephew’s class grew meal worms to see the life cycle of the Darkling Beetle.  I think I have the lineage correct;
First pair of larva were received in either Mid May or June.  They lived until August of this year.  The current beetle (as a mealworm) was hatched between mid June and July 1st.  So the beetle is approximately 5 months old.  According to the teacher and one or two websites,  the adult beetle,  should only live about a month.
My sister has taken over it’s care and feeding and replaces the oatmeal and apple slices regularly.
Is this the Methuselah of Darkling Beetles?   Or is this common for this critter?  I’ve attached a photo.
Thanks,
Doug Nickel
Mt. Washington

Mealworm Beetle

Hi again Doug,
Thanks for sending in your question.  The life expectancy of creatures in captivity can often be much longer than their wild counterparts if they are creatures that adapt well to living under the care of people.  Captive specimens that are fed regularly benefit from the captive diet and they are also free from predators.  Other than that general statement, we are uncertain if there are statistics on the longevity of Mealworm Beetles.

Letter 6 – Mealworm Infestation

 

Help?
Hello,
Please don’t ask where I took these photos but these "bugs", I am guessing larvae of some sort, were discovered in a refrigerator and freezer which has had no power for numerous months and obviously wasn’t cleaned out prior to the power being turned off. They are approx 1 inch or so long and kind of a grey color. I have a couple more pictures if necessary. Several of these things were seen on the floor and what I would "guess" is excrement can be found in large quantities near an open bag of grits. Trails lead from the cupboards to the fridge. There were no flies to be seen in the house, only spiders and fleas. Estimated count is well into the hundreds. We would like to fumigate this place and clean it out really well but would like to know what we’re up against first. Can you help us out? Other than using LOTS of bleach, are there any special precautions we should take (gloves and respirator a given)? Thank you in advance,
Dave

Hi Dave,
Your image isn’t detailed enough for an exact identification, but your vivid description indicates Mealworms. Mealworms in the genus Tenebrio are the largest Pantry Beetles. The size you indicate as well as the food source, the grits, makes this a near certain positive identification. You do not need special precautions when cleaning, just a strong stomache.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

5 thoughts on “Mealworm: All You Need to Know for a Sustainable Food Choice”

  1. Mealworms: one of the mainstays for developed-nation entomophagy.
    Along with house crickets, this species is the most commonly purchased and cultivated insect. I’ve worked with them in many preparations, as have lots of other people. Though I know of several instances where folks have developed allergic reactions to something about this species, independent of the usual insect consumption allergy.

    Dave
    http://www.smallstockfoods.com

    Reply
  2. Hello website

    I was cleaning my box of toys a month ago and under the box I saw 4 or 5 little worm Looking things with they were brown and have yellow strips or dots. After that I see them all over my apartment my apartment is covered with carpet and I see the bugs in the carpet. I would like to know if they are dangerous and what to do about them. We vacuum all the time we . I live in Canada by the way.

    Reply
  3. Hello website

    I was cleaning my box of toys a month ago and under the box I saw 4 or 5 little worm Looking things with they were brown and have yellow strips or dots. After that I see them all over my apartment my apartment is covered with carpet and I see the bugs in the carpet. I would like to know if they are dangerous and what to do about them. We vacuum all the time we . I live in Canada by the way.

    Reply
  4. I keep finding these very tiny black worms with what appears to be many legs and their skin shedding near my cat’s bowl of food in the am. Any ideas?

    Reply

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