Edible Caterpillars – A Potential Agroforestry Resource?

Edible caterpillars are a highly appreciated relish by local people in miombo woodland areas of Zambia. They are extremely nutritious with 60-70% protein on a dry matter basis, becoming available at a period when other high-protein foods are becoming scarce. Dried, they store for months and for a long period they can be found in local markets fetching high prices. No research has been done on them so far, but they may have considerable development potential. Caterpillar husbandry on a communal basis could probably increase the production of this valuable foodstuff very much if properly managed. Another fascinating aspect is that they might be used to reduce the number of late bush-fires, the reason being that in areas where the caterpillars are found people make sure they burn early because late bush-fires destroy the caterpillars. In areas where the caterpillars are not found late fires do considerable damage by killing trees, lengthening the regeneration period and increasing the damage caused by erosion. Since these caterpillars are found only in certain areas, they could be spread to new areas to give people there a good reason for early burning.

Mumpa

The edible caterpillar responsible for these impressive facts is the most important type found in the Northern Province of Zambia. It is called mumpa in the local language (Bemba) and is an emperor moth species [Saturniidae], which lays its eggs on the most common indigenous tree in Zambia, Julbernardia paniculata or mutondo in Bemba. The caterpillars are feeding on this tree in the beginning, but later also on 3-4 of the other most common trees in the miombo woodland (mutobo [Isoberlinia angolensis], muombo [Brachystegia boehmii and Brachystegia longifolial and mpasa [Julbernardia globisbra). The caterpillars eat the young leaves coming out just before the rains start. Trees may be completely defoliated, but new leaves come out when the rains have started. Forestry people have considered the caterpillars more as a pest – not so much because of the defoliation as for the damage done by people collecting them illegally in the National Forests, cutting down trees to pick them. Many watchmen are hired to protect forests from this kind of damage.

*We thank the author for permission to print this report (translated by the author) which was originally prepared as an unpublished mimeo in 1986. The author’s current address is Department of Agricultural Economics, Box 33, 1432 AS-NLH, Norway.

However, in the areas where the mumpa are now found in largest quantities north and east of Kasama, there is not much regrown miombo woodland left. Most of the bush consists of 1-3 meter high coppicing trees and bushes. This seems to be the perfect environment for the caterpillars and for human beings harvesting them without any cutting or climbing of trees. The mumpa has a very dynamic history which needs more investigation. It has spread from the west in an eastern and northern direction. Twenty years ago it was not found in the areas where it is now most common. And it is not found in large areas where it should have good sources of food, since the mutondo is found almost everywhere.

Traditional Laws and Beliefs

The main threat to the mumpa is probably human beings, who are too clever at harvesting the large spiny snack. This must somehow be understood by the local people because there are beliefs and laws regulating the picking season. The picking season is regulated by opening and closing dates which are usually 15th November and 15th December, giving a one-month picking season. The opening date is obviously to make sure that the caterpillars become big and fat before they are picked. The closing date is to secure enough “seed” for next season. The dates may, however, vary from year to year and the decision is made by the chief or even the paramount chief Chitimukulu. If somebody dares to start picking too early, it is said that he/she either will be bitten by a snake or killed by lightning. If somebody is caught, he/she will be brought to the chief and given punishment.

The same is the case for the closing date, but here the discipline among the people is much less and the picking in some areas tends to continue as long as caterpillars are found. “It is very difficult to stop picking this sweet relish! ” People come from far away to pick caterpillars and they do not listen much to the local laws and, therefore, the local people are discouraged and also continue the picking. It must become of major importance to re-establish the closing date of the picking season in order not to over-consume and destroy the caterpillar resource. However, most local people think that the caterpillars are a gift from God or the spirits and do not understand that they themselves may influence the abundance of the caterpillars.

Importance as a Food and Income Source

It is mainly the women who pick the caterpillars since the men are busy with cultivation of the land at this time though they might also go and collect caterpillars in the afternoons or even for whole days.

One person can pick about 20 litres per day if the bush is rich in caterpillars, the value of which in 1985 was K20. Thus 7 days’ picking should give K140 if all are sold and this is a month’s salary for a general worker in Zambia. Not strange that people travel 200-300 km to pick caterpillars. And traders come from Lusaka and the Copperbelt (900 km) to buy the foodstuff and sell it at a much higher price when they go back.

The caterpillars are no doubt the most important source of animal protein in the areas where they are found in abundance, protein deficiency being a major malnutrition problem in the area. Analyses have shown that they contain 60-70% protein on a dry matter basis.

Picking, Preservation and Eating

The mumpa has to be picked with care since it has spines, giving the collectors sore fingers. A special technique is used to squeeze out the guts in cleaning the caterpillars. The caterpillars die quite fast, dying on top of each other because of the spines. If they are eaten fresh they are fried, usually with onions and tomatoes and eaten as relish with nshima (ughali) – maize/cassava-stew. The frying process softens the spines so that eating is possible. They taste a lot better than those who are not used to them would think. Most of the caterpillars are preserved by boiling them for a short time and then sun-drying them for 1-2 days. They can then be stored for months.

Damage by Late Fires

The miombo woodlands in Zambia are largely affected by fires, causing a more or less fire-resistant vegetation. Still, fires late in the dry season, when it is very dry and the trees have started to produce new leaves, can do a lot of damage by killing trees, reducing regrowth and causing increased erosion. Protection by early burning is found to be the best way to avoid damage by late bush-fires. Complete protection is a lot more hazardous since people have so many good reasons to use fire, which then may easily go wild. In many areas it is difficult to encourage people to do early burning; they remember the laws forced on them during the colonial time. In 1985 1 observed that there were very few late bush-fires in the areas where the caterpillars are found. Once, however, late in the dry season when I was driving through this area with some Zambians we saw a bush-fire. (“A stupid guy has put it on fire, he wants to destroy our caterpillars!’)

When I traveled in other areas I saw a lot of damage by late bushfires. I investigated this further and found that in the caterpillar areas people make sure to burn early to protect their valuable relish from destruction.

Caterpillar Research
Very little is known about the ecology of the edible caterpillars. More basic studies are definitely necessary to determine if the potential is as promising as it seems. So far, the caterpillars have been totally neglected by the foresters and agriculturists who have been carrying out research in Zambia. The reasons are probably that most research in Zambia is carried out by expatriates and they have looked upon these insects more as a curiosity which they could not even think of eating or consider as an important foodstuff. Educated Zambians, however, agree that research should be carried out on the caterpillars. The question is which research field it should belong to. Agroforestry seems to me the best choice, since the caterpillars are a product feeding on trees which are a part of the local farming systems.

Questions research should try to answer:

1. Micro- and macro-studies of caterpillar ecology:
-Geographical appearance and importance.
-Dynamics. Why they are found in some areas and not in others?
-Life cycles: Lethal factors, climatic effects, multiplication.
2. Potential for development:
-Can caterpillars successfully be spread to new areas? Transportation of eggs is probably the best method.
-Could caterpillars this way be used as a tool to reduce the number of late bush-fires?
-Could caterpillar husbandry become a new established production organized on a community level (or will the resource be depleted as a typical “tragedy of the commons”?

Postcript. In a letter dated April 22, 1991, Dr. Holden provided additional information on his caterpillar proposal, in part as follows:

I spent most of the time 1985-1989 in Zambia, working as a junior researcher on a project, Soil Productivity Research Programme, where I was responsible for agroforestry research. I tried to forward a proposal for caterpillar research within the project but it landed on infertile soil among soil scientists and agronomists. “Serious researchers cannot come up with such things!” I ended up doing some private investigations and learned quite a lot about the life cycle of these insects (primarily the mumpa), about their geographical distribution at that time and in the past, how they easily could be transferred to other areas (as eggs) (we did a couple of transfer experiments but I have been unable to follow up and see if they were successful). I tried to make an agreement with a local chief (Chief Chimbola) to introduce caterpillars in his area but found it somewhat difficult to break through between my own scientific perspective of these insects and the local cultural perspective of the caterpillars. They were afraid of starting to experiment with them, they feared they would be punished by the spirits (the caterpillars are protected by strong spirits).

As you see from my mimeo, I was not interested in the management of these caterpillars only due to their importance as food but also due to their favourable impact on woodland management since they created the incentive for people to burn early and thereby enhance woodland regeneration….

Stein Holden
Soil Productivity Research Programme
Misamfu Regional Research Station