Breeding mealworms is one of the most popular topics on Youtube and there must be a thousand videos about this subject. Unfortunately, most of them aren’t much help if you are in any way serious about breeding lots and lots of mealworms. About a year and a half ago I started out with three containers, a bedding of oatmeal and carrots for a water source, just like they told me on Youtube. This worked out ok, but I only produced a couple of ounces of mealworms every week and they were all different sizes. It took me about half an hour every day to take care of them. Too much work for too little pay, I thought.
That’s when I decided to do some serious experimenting. I bought four Trofast storage combinations at Ikea with 36 containers. I made temperature controlled rooms out of them and I started three cycles of mealworms to experiment with. This way I could easily see the different results between the different cycles of mealworms. I experimented with things like bedding, temperature, food, moisture etc. and this paid off very well. With just one cycle, I could now easily produce 2 pounds of mealworms every week. This is over four times as much as I could with my first setup.
Before we talk about mealworm food, I’d like to share two things with you. I found that the most important factor for success is their housing. The only way I could achieve this was to use a lot of containers. I sift out the eggs from the beetles weekly so I need one new container per cycle every week. Considering they need about 9-10 weeks to be full grown, that’s a lot of containers. The second important thing is temperature. Their frass (droppings) seems to really attract heat and if the containers get too hot, lots of mealworms will die. So sifting often is very important. If the temperature is too low, they just won’t grow. I keep them between 77 to 86 degrees (25-30 C).
After reading a lot about mealworms I found that in their natural environment they live in rotting wood. They can digest the cellulose in the wood but their main source of food would be the microorganisms living in it. In the past I had some experience with sourdough for baking bread and I knew there are lots of microorganisms in it. So I came up with the idea of mixing sourdough with my mealworm food. A crazy idea, but I was stunned by the results. With my ordinary food it took them up to 14 weeks to become full grown. While with this new food, it only took them about 9 weeks.
On the internet you can read a lot of romantic, even mystical stories about sourdough. I would definitely advise you to read some of that stuff. There’s really not much to it though. You’ll need a jar and a warm place to keep it. First you make your starter with the same amounts in weight of flour and water (for example 3 ounces or 100 grams) and a little wheat bran and stir it well (see below for a specific recipe). Every day you remove half of the mixture to use for food and add to the original container the same amount of water and flour (no wheat bran). Within a week, you’ll have a nice bubbly substance you can use to bake bread with, or in our case feed mealworms with.
Sourdough has a very specific smell and the mealworms love it. When I start feeding in one container, the worms in the other containers come to the surface very quickly because of the smell. The only problem with sourdough is that the flour in it gets really hard when it dries. If I feed the mealworms too much, they get stuck in the hardening flour and some of them will die.
Because cutting carrots daily was a pain, I started looking for a replacement for them. Carrots are really only needed as a water source. The worms can easily survive on bread and water. So I replaced the carrots with other stuff that would absorb a lot of water. I tried saw dust, wet paper, soaked horse food, soaked wheat bran and sugar beet pulp. I even tried water crystals but since humans could one day eat the mealworms ourselves (an ongoing conversation in Europe), I’m a bit concerned about feeding them the chemicals they use in a baby’s diaper. All of these water absorbing things seemed to work to some extent but most of them would dry and lump up with the sourdough, making it almost impossible to sift the worms.
This is why I’m picky about what they eat: we could be eating them one day.
Then I came up with an idea: I would no longer use flour. I would use a base of soaked wheat bran as a water source and breed the microorganisms in it. To get them continuously growing I would replace half of my food every day, like I would with sourdough. After experimenting for a couple of weeks with different ingredients I finally noticed the alcohol-like smell I was looking for. There’s a bit of a rotting smell too, which I’m still trying to get rid of. The mealworms don’t seem to mind though. I call this my “sour mash wheat bran” after an old hobby I used to have: making sour mash moonshine.
Here’s my recipe: In a bucket you add 6 cups (1.5 liters) of lukewarm water, 3 table spoons of dextrose, a few hands full of fine chick’s food and while stirring, you add as much wheat bran as it takes to get the mixture so dry it’ll really fall apart in your hands. Keep it overnight at room temperature or preferably a little higher. Every day you feed about half of the mixture to the mealworms and add the above ingredients to the remaining mixture again to make more food. Just be sure to dissolve the sugar in the warm water before adding it, or the yeasts will die and you’ll have to start over. After a couple of days you’ll clearly smell the produced alcohol. That’s when you know the process is really going on.
I would say the worms like the real sourdough better so I’m certainly not done experimenting yet. Maybe some of you will continue where I left off and share your experience.