how to grow mealworms at home

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How to grow mealworms at home

Introduction on how to grow mealworms at home

how to grow mealworms mealworm binMealworms are renown as food for animals like birds, fish, and reptiles. But the mealworm also gains popularity as a food source for us, humans. It’s said to be a good replacement for meat products. And as it seems impossible to grow enough meat to feed the world, insects could be a good substitute. In warmer regions, insects are already on the daily menu.
I personally don’t grow mealworms to eat (although the way I grow them, I could eat them). I grow mealworms for my chickens. As a side-dressing for the chickens it contains a lot of protein and fats so especially during the winter time it can be very useful and cheap. Don’t ever only feed the birds mealworms as this is certainly not a complete food for the chickens.
In fact, mealworms are the immature form of the mealworm beetle or flour beetle, in Latin called tenebrio Molitor. The beetle lives in decayed wood but can also be a pest for farmers and millers, as the name mealworm is not unfounded. The beetle also lays eggs in flour and grains of flour and grain processing industries.
The mealworm beetle itself doesn’t contain any useful nutrition and it contains a lot of fat and therefore is only usable as a production animal. The beetles are pulled out of the bins to be put in new bins and reproduce.

The growing system

So let’s talk about how to grow mealworms at home.

Standard system

The easiest and thus most popular system consists in the beginning of 2 plastic bins. Some use 3 bins because they separate the beetles from the pupae. I personally only use two bins because I don’t see that much damage done to the pupae from the beetles.
One bin is used to grow the mealworms.
A second bin is used to put the pupa in as these are vulnerable to attacks from the meal-worms. That’s where the beetles will grow out and lay eggs.
If mealworms and mealworm beetles don’t get enough moisture, they can become quite cannibalistic and start munching on the pupae 
When the beetles emerge, we have to keep them in the second bin for at least 3 weeks, even better is 4 weeks so they have enough time to lay eggs. We have to start counting from the moment there are enough beetles in the bin to procreate. The females need to mature for at least two weeks before they start laying eggs so we keep them those 2 weeks plus another 2 weeks to lay eggs, in the same bin.
After this first month, we put the beetles in a new bin every two weeks as there will always be mature females from now on. It is necessary to harvest every single living beetle from the bin with eggs as beetles also tend to eat eggs.

 Personal experience on how to grow mealworms

how to grow mealworms mealworm on handI personally only keep the beetles for about 2 months. After this period, the females don’t lay as many eggs anymore and I just feed the beetles to my chickens.
After the eggs have been laid, it takes some time for the mealworms to become visible. In their first weeks, the mealworms are almost not visible to the naked eye.
Only after a couple of weeks, you’ll see the small critters running around. So don’t give up if you think after some time nothing is happening. Be patient and you’ll be rewarded.

the culture medium

I personally have only one bedding I use in the 2 base bins and the following bins. Wheat bran is the only bedding I use. The mealworms don’t seem to need anything else and it works out fine. The only other thing the animals need are materials to absorb moisture. So I use slices of potato, apple, carrots, and leaves of weeds and vegetables to feed and moisten the small critters.
I also add a little bit of meat bird food because the females do need a certain amount of protein to lay quality eggs.

The bins to grow the mealworms in.

I personally use plastic bins with a minimum height of 10 cm or 4 inches and the sides have to be straight up. Diagonal sides give the mealworms the chance to escape. I never used anything to prevent the beetles to escape and had almost no escapes in the time I grew and grow mealworms.
Plastic bins are practical for two reasons. The first reason is the fact that neither beetles or worms can munch through the plastic.
The second reason concerns hygiene. An aquarium or terrarium can get infected with fungal diseases or mites and is really difficult to disinfect, rinse and dry out. A plastic bin with rounded edges can be disinfected, rinsed and dried in an easy way.

where to grow mealworms in how to grow mealworms?

My mealworm bins are inside the house in the heated basement. The basement has an average temperature of about 22°C or 71,6°F and it’s relatively dry.
Under normal, wild conditions, the mealworm beetle and the mealworms live in a relatively cold system in decayed wood or in grain barns. In these barns, they can be real pests.
Although the common situation is quite cold, it’s best to keep the mealworms in a room where the temperature is above room temperature to let them grow faster and digest more readily. The best temperature is around 25°C or 77°F but as I grow composting worms too, I keep the temperature at about 22°C or 71,6°F.
So, keeping the critters in a bedding of wheat bran with some pieces of fruit or vegetables as a source of moisture and keeping them at least at room temperature, is more than enough to grow the critters without any problem.

the four phases of the mealworm beetle

how to grow mealworms pupa on handThe four different phases of the mealworm beetles have to be separated into different bins. So what are these four different phases?
The different phases are explained for a temperature of about 25°C or 77°F.


The first phase is the egg. This phase takes about 2 weeks. The eggs are about 1,5 mm long or 0,06 inch long. They are white and sticky so they stick to the bedding quite easily. This phase is a really weak phase and a dangerous phase because the females that lay the eggs are in need of lots of proteins to produce those eggs. As every moving phase of mealworms is very cannibalistic, it’s very much possible that one female eats the eggs of another female to produce her own eggs. I personally make sure the critters have some chicken feed to get their proteins from, to avoid most of the cannibalistic traits.
The female beetle can lay about 150 to 200 eggs in a period of several months. As these eggs are sticky, they get a good camouflage by sticking to the bedding. Although the camouflage works, it’s always good to give the beetles some toilet paper rolls and some pieces of cardboard to lay their eggs under.

The mealworm itself

The mealworm or the larva is the actual object that’s part of the trade amongst humans and that’s eaten by a lot of animals and some humans.
The larva starts as a really small animal of about 1 millimeter long. It systematically molts and grows in different steps until it reaches about 4 cm long or 1,57 inches long. The mealworm can molt up to 20 times before it reaches the right length to turn in to a pupa.
The growth of the larva goes in different steps because the critters can only grow in the short period where they have just thrown off their former skin. Once the chitin skin has hardened again the mealworm stops growing until it sheds it’s skin again.
Shedding the skin is visible in the bin because of two things. First of all, after a couple of days, we’ll find a lot of empty skins in the bin. Second of all, the new skin of a mealworm is white, so we’ll see a lot of white mealworms that turn darker after some time when the skin hardens again.

The pupae of the mealworm beetles

The pupa forms when the mealworm has reached an average length of 4 cm. In this phase, it sheds it’s skin and changes its appearance. Now it already looks like a beetle but it is a kind of cocoon.
In this phase, the critters are quite defenseless as they can only wiggle their tale to avoid being eaten. So, the first time you hold a mealworm pupa in your hands, don’t be shocked when you see it wiggle around. As these pupae are almost defenseless it’s better to keep them in a separate bin where they are safe from predators.
The pupa needs about two weeks to develop into a real moving beetle.
When the pupae turn into real beetles, it’s best to remove them from the pupa bin and place them in the next bin. This way the mealworm beetles don’t start munching on the other pupae in the bin. I personally don’t do this step anymore because I have seen that there’s no cannibalism when the critters have enough protein and moisture in the bin. But just to be sure, until you have found the right amounts, it’s good to split them up.

The mealworm beetle

After the third phase, we finally go over to the final stage, the adult beetles. In this phase, we have creepy crawly bugs and some flying beetles who will make sure there’s the next generation. The first two weeks of their existence the female beetles can’t lay any eggs yet. After those two weeks, the egg production goes on until they die.
At first, we’ll see a white beetle. After some time it’ll turn golden brown and finally it’ll turn totally black.
The mealworm beetle is about 1 cm to 2 cm long ( 0,39 to 0,79 inch)
The lifespan of the beetles is about 3 to 4 months.
I personally don’t keep them that long around as the egg laying goes down tremendously after the second month.

Mealworm frass

how to grow mealworms siftedWheat bran consists of quite large flakes. These flakes are the bedding for the mealworms but also their food. Once the flakes are chewed through it turns into mealworm frass or mealworm poop. The poop consists of really small particles that go through a kitchen sift very easily. So cleaning out the bin consists of sifting through the bedding and setting the frass aside. If the bedding was used for the mealworms, you can easily use it as a good fertilizer for the plants. If the frass comes from a bin with beetles, put the frass aside for a couple of weeks to make sure you can sift out all of the small mealworms after a while.
To gather the young mealworms to the top of the layer, you can put a carrot or potato on top. The mealworms will congregate around the potato. That way, you can easily get them out of the frass.
The mealworm frass is a totally organic fertilizer with an average N-P-K value of about 4-3-2.

sorting mealworms

With the right size of mesh, it’s easy to sort the mealworms to different sizes.

how to grow mealworms beetles in handI personally use a sift with 3 mm holes to sift the pupae and the beetles from the mealworms. The mealworms go right through and the pupae and beetles stay on top.

The same sift is used to place the beetles to their next bin when laying eggs.

Another system that is used a lot is the use of toilet paper rolls and egg boxes. Beetles tend to climb in the cardboard pieces and are easy to remove.

Above mentioned systems won’t work for 100% and that’s okay. Don’t be a perfect freak like me. In the past, I was doing hours of work to sort every single beetle or pupa out of the bins until everything was clean and tidy. Once I started working with 10+ bins that became impossible to do. So I adapted, and guess what, it also works.

closing on how to grow mealworms

I think I said about everything there is to know on how to grow mealworms at home.
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