How to Breed Mealworms

Co-authored by Samuel Ramsey, PhD

Last Updated: September 5, 2024 Fact Checked

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If you have hungry reptiles or fish to feed, breeding your own mealworms is an excellent way to save some cash and ensure your pets are getting proper nutrition. Mealworms are actually darkling beetles in the larval stage, so breeding them involves allowing the beetles to mature and reproduce.You'll need a few large containers, mealworm substrate, and a collection of mealworms in order to start your own colony. After a few weeks of waiting in anticipation, you should have a healthy batch of mealworms at the ready!

Part 1

Part 1 of 2:

Setting Up Your Equipment

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1
Purchase suitable bins. You'll need shallow bins with smooth walls made of either glass or plastic, so that the worms and beetles aren't able to climb out. 10 gallon (37.9 L) fish aquariums work very well, as do plastic storage containers. The containers need tops with tiny vents or airholes (wire mesh works, as does poking holes in the lid) that allow for airflow without letting the mealworms escape. Darkling beetles can't fly, but a lid is a safety precaution that you should have.
- Getting at least two (three, if you want to start a very large colony) is essential because you'll need to separate the beetles from the larvae a few weeks into the process. If you fail to separate them, they will eat one another.
- Do not use wooden containers, as mealworms are able to eat through these.
2
Prepare your mealworm substrate. Mealworms feed on grains and cereals, and that's what you'll need to use as substrate. You can buy mealworm substrate from a feeder supply store, or you can make your own mixture from bran flakes, corn flakes, oatmeal and other cereals. The substrate should be ground to a fine powder to make it easier to pick out the worms and beetles when you need to move them.
- Depending on the needs of the pet you are feeding, you can add bone meal, cricket chow or other ingredients to change the nutritional profile of the mealworms.
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3
Buy mealworms. The number of mealworms you buy for your starter stock depends on how many animals you aim to feed. If you need to use the meal worms to start feeding the animals right away, aim for 5,000 or so to begin with.^{[1]
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Research source} It takes a few months for the mealworms to reproduce, so this population will get depleted at first.
- If you don't mind waiting a few months for new mealworms, you can start with as few as 150 mealworms.
4
Set up a stable growing environment. Mealworms reproduce best when they're kept at a steady temperature of 70 to 75 °F (21 to 24 °C).^{[2]
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Research source} Choose a place in your home where you can keep the temperature consistent. The area should be clean and free of chemicals that could contaminate the colony.
- A heated garage or basement would be the optimal place to keep your mealworms.
- You can buy a heater to use near the containers to keep the temperature steady for your mealworms.
- If you keep the mealworms too chilly, they won't reproduce.
- Mealworms prefer a little bit of humidity in their environment—just make sure it isn't too humid, or else fungi might begin to grow. You can get a humidity meter online to help maintain a good balance.

Part 2

Part 2 of 2:

Breeding the Mealworms

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Line the first bin with 2 to 3 inches (5.1 to 7.6 cm) of substrate. Place your starter stock in the bin. Slice up an apple, a carrot, or a potato and place the slices on top of the substrate, to provide moisture for the mealworms. Put the lid on top of the bin. The mealworms will begin eating the substrate and reproducing. The mealworms may pull the food under the substrate to eat it, which is completely normal.
2
Wait for the mealworms to reproduce. The mealworms, which are the larvae of the darkling beetle, will need 10 or more weeks to go through their life cycle and reproduce to make new mealworms. They will change from larvae to pupae, then from pupae to mature beetles. The beetles will copulate and lay eggs in the substrate, which hatch 1 to 4 weeks later.^{[3]
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Research source} While you wait for this process to take place, check the bin every day and take care of the mealworms in the following ways:
- Change out the cut vegetables if they appear to get moldy.
- Keep the temperature stable at 70 to 75 °F (21 to 24 °C).
- Remove dead mealworms or beetles and discard them.^{[4]
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  Research source}
3
Move the beetles after the eggs hatch. Once the new larvae hatch from their eggs, you'll need to move all the pupae and beetles to the second container. If you keep them all in the same container, the beetles will feed on the larvae. When you move them to the second container, they'll lay eggs and continue the reproduction process. To move the beetles and pupae, do the following:
- Prepare the second container by lining it with 2–3 inches (5.1–7.6 cm) of substrate.
- Pick out the beetles and pupae by hand and place them in the new container. Use gloves if you want to. The beetles won't bite and rarely fly.
- Put a few slices of carrots or potatoes in the second container, then cover.
4
Feed the mealworms to your pets. Once the new larvae are big enough (before they become pupae) you may feed them to your pets. Remember that any mealworms left in the bin will mature and become pupae, then beetles. Continue moving pupae and beetles to the second container as they mature.
- You can store mealworms in the refrigerator to make them keep longer if you want to set some aside for feeding your pets.
Once the life cycle has completed in the first bin, the substrate will be depleted. Pick out all remaining mealworms and place them in a clean bin while you disinfect the first one. After cleaning and drying it thoroughly, add a few inches of new substrate, then replace the worms in the bin to begin the process again.

Community Q&A

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Question

How do I use cheesecloth when breeding mealworms?

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You can cut out the bottom of the container you keep your beetles in, the beetles will dig down to the bottom to lay their eggs, the eggs will hatch, and the little hatchling will burrow down further to prevent being eaten. Thus it crawls through the cheesecloth, into the bin beneath with the other mealworms. Check YouTube for tutorial videos.

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When the beetles lay eggs after a few weeks there are transparent things crawling all over the place. Can you tell me what this is please?

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Those are the larvae that just hatched. If you haven't already, move the adult beetles immediately, so they don't eat the larvae.

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Seems to take a long time for my baby mealworms to grow big enough to use as treats. Why is that?

Caeiia

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May not be the right temperature or enough good food sources.

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You need to keep it in a warm dark place. Don't keep it in a cold place.

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The more surface area the better.

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Check on them often.

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Cut a hole in a bin with the beetles and glue a screen to the bottom. When the beetles lay eggs, they'll fall through and turn into mealworms. Then, you won't have to separate the beetles from the worms.

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Warnings

Some mealworms need to be separated from each other to pupate. They can be put together after they pupate.

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Things You'll Need

A large bucket or tray (plastic or metal, 8 - 10 inches deep and the larger across the better)
Burlap (a few squares of it)
About 100 mealworms to begin with
Fruits, veggies, oatmeal (fresh)
Paper towels
Sand
Cheesecloth