Mealworm (Tenebrio molitor). Food and more

Today we go a bit out of the ordinary, to talk about insects, but not about insects as pests but about those that are susceptible to being eaten and are perfectly suitable for human consumption, such as the mealworm ( Tenebrio molitor ). FAO has said on several occasions that given the overpopulation that we already are and that we will be, the protein diet based on insects instead of meat is the future. Well, it is the future. Slimy… but tasty!


The Homo sapiens as a species is omnivorous and nutritional contribution, as we know, is based on a varied diet of fruits, vegetables, cereals, fish, meat … in that order from highest to lowest frequency as we all know. The fundamental problem is that in the West, this food pyramid is inverted, with an increasing consumption of meat (much of it processed) and less and less of fresh vegetables and fruits . But this is another point to analyze that we are not going to delve into today.

As we know, the vast majority of protein intake is obtained from meat, from the muscle of animals, and producing that meat has a significant environmental impact . Animal production systems have reached frightening levels of modernization, in order to supply the demand for meat around the world. This entails a huge environmental cost in carbon footprint and water footprint per kg of meat produced.


The relationships between agricultural production systems are so intricate and sometimes so complex (although it may not seem like it), that the consequences derived from an agricultural or livestock activity can be enormous at a global level.

We all have the bucolic image of the cow grazing in vast green meadows, but the reality is very different. The production of meat worldwide is far from that image that is relegated to extensive and local productions, but it will never be the meat that we find in the supermarket.

The image does not want to reflect the excessive and abusive housing of the animals. Stabling is a practice that has been done for centuries and in extensive livestock farming it is done, being very necessary to maintain stable production and ensure the protection of animals during the winter months and at night (predators in some cases). It is simply a didactic image to globally illustrate what we usually imagine when reality is quite different.

We have to be aware of the true global magnitude of meat production starting with deforestation to grow the cereals that will give rise to the feed to feed them. It is not only the environmental footprint that this leaves, but also the deforestation itself, which eliminates a large plant mass that consumes Co2 . The damage is twofold. Later we will talk about it in addition to the cost of meat production.


Here we find ourselves with a rather complicated dilemma to address and that appeals to individual, social and environmental responsibility . We are already several generations used to recycling, to having 2-3 or 4 different garbage cans at home where we separate to try to recycle materials for daily use. We have come to go through that hoop, a situation that surely six years ago would be unthinkable and that many people from then do not even understand.

With this, we come to say that the changes of uses and customs at a general level cost a lot to modify them , and that they now tell us that we must reduce our consumption of meat “drastically”, and especially of processed meat, we have a lot of “fiber »And not the muscular one.

In the video of Jose Luis Crespo , a YouTuber admired by the editors of this blog, he tells us 26 ways to alleviate climate change and at 6:39 minutes he addresses the issue of diet and reducing meat consumption. The entire video is worth watching but we give it to you to eat if you don’t have time.

Conclusion from Crespo’s video: By reducing the consumption of meat (especially beef) our impact in terms of carbon footprint is considerably reduced, taking into account all the aspects that influence animal production. From the deforestation of wooded areas to grow feed that is then eaten while growing up, to transport, infrastructure, water consumption blah blah blah …


We mainly buy meat, beef, pork, lamb and poultry. Chicken, pork and beef are the most consumed types of meat in Spain and we rarely think about the cost of producing such food. We are going to do a reflection exercise and then we contribute data to have a certain order of magnitude.

If we think of animal production as a conversion of inputs and outputs, as an industry of «inputs and outputs», making a reduction to the absurd we can consider that:

  • The “inputs” are mainly feed and water, as well as medicines (antibiotics), conditioning of ships, transport, etc. etc.
  • The “outputs” or outputs, the kg of meat that we remove for sale to the consumer.

Therefore we arrive at very simple magnitudes that help us to compare the cost efficiency of producing one kg of mammalian or bird protein versus producing one kg of protein from some edible insect. These could be translated into:

  • kg of food per kg of final protein obtained.
  • liters of water per kg of final protein obtained.
  • Amount of CO2 equivalent per kg of final protein obtained.

The last two are what we could call the water footprint and the carbon footprint, respectively, that we have been hearing so much in recent years.


Well, hold on to the males as my grandmother used to say because here come the comparisons. According to FAO (The Food and Agriculture Organization of the United Nations) we have to:

  • Insect farming can produce 1kg of edible insect mass for every 2kg of feed . Cattle on average produce 1kg of meat for every 8kg or 10kg of feed.
  • The emission of greenhouse gases is another scary fact. Pigs, for example, emit 10 to 100 times more greenhouse gases than insects on average. I know that from 10 to 100 there is a very wide margin but even if it was only half, (50 times more) it is already an absolute nonsense.
  • If we go to the water footprint, we find that for every 10 liters of water about 8kg of insect is obtained , as opposed to 2kg of chicken meat, or just 900g of beef.


  • Insects can feed on food waste of human origin, compost, manure etc. These would be used to make flour and feed for livestock in turn.
  • Traditional cattle require much more water than insects. These are quite resistant to drought, especially the mealworm we are talking about today.
  • Traditional livestock are much more dependent on land use and land area than insect rearing.

Click on the link if you want to see more about the FAO document.

In other sources consulted, for example, we have that, on average, 10kg of food produces:

  • 1kg of beef.
  • 3kg of pork
  • 5kg of chicken meat
  • 9kg of edible insect (still not able to call it insect meat).

As we can see, the efficiency of these bugs is nonsense. Let’s keep going:

For the same amount of feed, pigs produce 8 to 12 times more ammonia (from slurry) than lobsters and about 50 times more than crickets.

The data is devastating, full stop.


But let’s go to the mealworm. We have not treated it in Gardenprue as a crop pest because, in reality, its action phase does not occur in the cereal production phases as occurs with other pests. Let’s see where this friend appears based on the etymology of his scientific name .

We start with the genus, Tenebrio , which belongs to the Tenebrionidae family large family of about 20,000 species of coleopterans, that is, beetles .

If we talk about beetles and what concerns us is a worm … we can infer after a brainy and arduous work of deduction, that the mealworm is the larval stage of the Tenebrio molitor beetle To show a button. Here an image of the larval stage and another of the adult stage of this species.

Let’s continue with the “last name” molitor. Word that refers to a mill, effectively the grain mill, where flour is produced because that is precisely where this plague attacks. Once the grain is ground and the flour stored in large silos or sacks, this is when this funny beetle takes the opportunity to lay its eggs , a rich environment where the larvae will develop optimally, feeding on the nutritious and rich cereal. In fact, it is also known as a tree worm .

The consequence of this pest is that the quality of the flours is considerably reduced , spoiling tons of it. Hence, its control in flour mills, storage silos, etc. be so important.

But today we have not come to talk about how to combat the mealworm, we have come to talk to you about it as food, as a substitute for protein source against meat and about other recently discovered uses that can help us in reducing the environmental impact produced by plastics, specifically polystyrene.


Digging around, we have been able to find that the mealworm is an impressive source of protein, as well as a memorable source of lipid. What’s more, its fat content makes it a fairly caloric food. Let’s see:

In a 2012 study evaluating the nutritional potential of two species of insects in the larval stage, including the mealworm, it was determined that:

The protein percentage of the mealworm ( Tenebrio molitor ), in its larval stage is 46.44%. This data is understood considering the dry larvae (without any water content). As we will see later, the protein content in fresh is much lower although it is still high.

Within this protein, its quality was found to be high, being rich in amino acids such as isoleucine, leucine and lysine. Its composition in fatty acids has a high content of oleic C18: 1, in addition to linoleic C18: 2 and palmitic C16.

Another article from 2013 ” Larvae of mealworm ( Tenebrio molitor L. ) as European novel food ” tells us:

The nutritional value of the fresh larva was analyzed (without removing the humidity) with 3 months of development, about 25-30 mm and the data obtained are:

  • 56% water content
  • 18% total protein content
  • 22% fat content
  • 1.55 in ash (gives us an idea of ​​the content of important minerals).

Among the minerals we have high levels of magnesium, zinc, iron, copper and manganese.


Finally, the ratio of fatty acids n-6 / n-3 (omega 6 / omega 3) was 6.76. This figure is actually quite good and close to the ideal of 4: 1.

The Western diet far exceeds the ideal of 4: 1. And that’s not good. Without going any further, the Mediterranean diet has a 25: 1 ratio on average and we have it as a healthy diet !!. It is, but the Mediterranean diet is not exactly the current one. Throw in a lot of legumes, and little meat actually.

These values ​​mean that it can be considered without any doubt a food of high nutritional value both for animal feed and for human consumption.


If that were not enough its nutritional value and its efficiency in the global cost as food or feed for livestock, in addition it has recently been discovered that the mealworm degrades certain plastics. Obviously we could not use the same worm for nutritional purposes feeding it with plastics.

But it is interesting to see the open way that this quality has to degrade plastics as abundant as Polystyrene (PS) or Polyethylene (PE).

And it is not that the worm degrades it by itself. Rather, it is due to the bacterial flora of the mealworm itself. Among them, the species of the genus Exiguobacterium sp There are specific strains of the digestive tract that are capable of degrading it, as the following study illustrates 

In another study , other strains such as Citrobacter sp. and Kosakonia sp. associated with the degradation of polyethylene specifically and how the ingestion of this can affect the intestinal microbiome. The results suggest that the adaptability of the mealworm gut microbiome allows the degradation of chemically different plastics (PE and PS).


After all this reflection on the mealworm and the viability of eating insects or not, it remains to ask oneself if we would be able to put this and other edible insects in our mouths.

I have particularly eaten grasshoppers, ant larvae and maguey worms in Mexico and they are authentic delicacies. Here’s an example of a taco with guacamole and maguey worm that I gobbled up. Delicious, really.

As is always said, it is difficult to integrate something like this into a European gastronomic culture but we must not forget that we eat live oysters, snails, barnacles, razor clams , a lot of sea crustaceans such as prawn, Norway lobster or crayfish. They are really ugly critters and can “back off” more than one who is not used to them.

If you are from Spain you will know that we are one of the largest producers of rabbit and in most of the world, eating rabbit with garlic or in a paella is a brutal abomination. Our Iberian ham, in other countries they think that we eat practically raw meat. Cultural issue.

The same thing happens with the mealworm, a cultural issue and at the rate we are going … global necessity.

Let us know in the comments if you would eat mealworm, and if you have already tried it… tell us how it was!

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