Mopane worms – high protein food in Africa

Mopane worms (Instars of Gonimbrasia (Imbrasia) belina) are mainly found on Mopane trees (Colophosperma mopane), but also on Wild Syringa (Burkea africana), on Zebrawood (Microberlinia Brazzavillensis) and others. However Mopane trees are a highly dominant species in climates and areas befitting them, also a concentration of Emperor moths occur in such areas. And associated with that also vast numbers of Mopane worms.

Distribution of Mopane worms

The densest distribution of Mopane worms is hence in areas dominated by Mopane trees. Mopane trees prefer poor soils, harsh climatic conditions, and a low amount of nutrients. In pure Mopane veld, no grass is growing anymore, as Mopane trees are growing so dense. Such conditions occur in norther-eastern parts of South Africa, southern Zimbabwe, northern parts of Namibia and Botswana, and parts of Mozambique, Zambia, and Angola. Generally speaking, due to climate change, the Mopane belt is moving southwards in these areas at a speed still not agreed upon by scientists. See here. And therefore, also traditions and cultural implications for local populations are and will further be changing.

Life cycle

A Mopane worm life cycle is quite interesting. The female Emperor Moth lays eggs on a leave or twig of the host tree. After hatching around October, the caterpillars go for four molding stages through five larval instars. During that time, the caterpillars consume nearly all of the Mopane leaves on the trees. And by their defecations, they create a dung carpet, which gets quickly recycled into the ground. From February onwards, pupation occurs over wintertime for 6 – 7 months. And around September the moths will fly out. Both males and females will only live for some days in which they are mating and thereafter will die. And the life cycle starts from the beginning again.

Mopane worms as human food

Mopane worms are for the local population a delicacy since millennia of years but should only be consumed by persons with no allergic reaction against penicillin.

When in summertime the caterpillars are out, locals collect them in great numbers. After harvesting, they squeeze the internal contents of the caterpillars from head to backside out of the body. Thereafter they wash them and either briefly roast them on a griddle and dry them, or directly dry them for later use. Roasting is done for singing off the stingy hairs on the caterpillar’s body. Remaining are the thorny spikes, making chewing the worms in the mouth unpleasant.

Preparation of Mopane worms by Ndebele people

Ndebele (Matabele) in southern parts of Zimbabwe roast them in such a way, that they light a huge fire and create a hole in the middle of the fire. That’s a ‘ring of fire’. Thereafter they put the cleaned Mopane worms inside this ring of flames and let them singe off their hairs and cook them evenly. Burning them will be avoided by constantly shuffling them around. This fire has to be quite intense, as the caterpillars contain lots of water. Thereafter, they are taken out of the ring of fire and scrubbed with fresh leaves to remove all remaining hairs on them. But still: the spikes remain. After this preparation, they are getting finally sun-dried and put into storage.

Cooking Mopane worms

There is a multitude of cooking methods besides eating them raw. The most popular methods are to cook them with onions and tomatoes or just roast them with a bit of oil or fresh cream. We did it the traditional Ndebele way by just roasting and eating them as a crunchy snack.

Before use, the dried Mopane worms have to be reconstituted again. Put them into a bowl and cover them generously with boiling water for about 20 minutes. Thereafter they have to be cleaned with this water and stretched. In our case, there was no sand or debris on them and also the inside was nearly clean of foreign matter. But every segment of the caterpillar has to be stretched out to make them flexible and chewable again. After initial cleaning in the veld, many caterpillars contract their body segments into a tight bunch. And when being dried, they end up as a hard clump of caterpillar. Stretching out the reconstituted bodies will make them easily edible. This stretching can be sometimes painful, as the body spines on them are still fully intact. And to my knowledge, there is no practical way to remove them.

Frying them in oil – Ndebele people like to use ulaza (fresh cream) instead – is the easy part. And salting them, when nearly ready to eat.

Eating- and nutritious value of Mopane worms

As mentioned above, the worms were in our case clean on the inside, and there were no traces of Mopane leaves or other foreign matters to be seen. When eating them, the prominently felt texture was that of the tough outside skin with a bit of pleasant, chewy matter inside. The taste of the worms was like sweet meat, which was intensively flavored with a tea scent. For me, it subjectively tasted like Pu-erh tea in China. That’s mainly because of the high contents of phenols and tannins in their favored food of Mopane leaves.

Tswana people remove the black head before eating the caterpillars. Every worm has an average of 18% of chitin content (head, backside, spines, …), which blocks digestive enzymes from accessing protein and lipid substrates and thereby reduces the utilization of these nutrients. If possible, these black matters therefore should be removed before eating.

According to this source, 100 g of Mopane worms have got following nutritional value:

Energy value: 124 kcal

Proteins:                     58% dwb (dry weight basis)

Fat:                             15% dwb

Carbohydrates:           8% dwb

Minerals:                     1,34% dwb

Fiber incl. chitin:         17,7% dwb

These caterpillars are rich in protein and have significant values of fat (of which 38% of fatty acids are saturated and 62% are unsaturated) and fiber. The fiber content – as mentioned before – is to a high degree antinutritional and should be removed before eating. 

Lessons learned about Mopane worms:

  • Mopane worms have five instar larval stages.
  • After collection, their internal gut content has to be squeezed out.
  • Cleaned Mopane worms have to be singed to remove irritant hairs on their body.
  • There are two main styles of cooking them and a multitude of other recipes.
  • After reconstitution dried Mopane worms, have to be stretched to make them flexible.
  • These caterpillars are rich in protein and fiber.
  • Chitinous parts should be removed before eating.

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