Edible Caterpillars in Bas Congo

Paul Latham

Background

I have been involved in a development project in the Bas Congo province of the Democratic Republic of the Congo during the past 21 years. This commenced as a beekeeping project but has evolved into a more general rural development programme. The production of edible caterpillars, on which my talk will concentrate, forms part of this project. Farmers practice a traditional system of shifting cultivation in much of Bas Congo allowing a forest fallow to build up soil fertility over a number of years. Due to increasing population and lack of fertility the length of fallow has shortened from between 15 to 20 years to sometimes as little as 4 or 5 years. Yet the forest and its by-products, in addition to timber, firewood and charcoal, are of vital importance to the rural population. They include various vegetables and fruits, mushrooms, edible insects, medicinal plants, honey, tying materials and the protection of water sources, so that any loss of forest fallow significantly affects the quality of life.

Insects as a food source

Insects, like these Oryctes beetle larvae or palm worm (slide 1), generally represent an important part of the diet of much of central and southern Africa. Nowhere is this more the case than in the Congo. A study of animal protein consumption in Cataractes district of Bas Congo, where the project operates, found that 12% of animal protein consumed was from insects (Gomez et al 1961). Many insect species are pests of a wide variety of crops throughout the world. Enormous quantities of expensive, toxic substances are used to kill them yet many of these species are edible and traditionally have provided people with an important source of protein (Ramos-Elorduy & Pino 1994). It is perhaps ironic that farmers frequently save crops that contain no more than 14% protein while killing insects which may contain over 75% high quality protein (Ramos-Elorduy 1997). Insects in general have good food conversion rates offrom 4 or 5 : 1. Though poultry may be more efficient (2.6 : 1), insects have the advantage that they convert plant material that is often not consumed by humans into a highly palatable food.

Edible caterpillars

Caterpillars are an important traditional source of food in Bas Congo. In common with much of central and southern Africa, they provide a valuable source of protein in a diet otherwise very deficient in protein. Fish and meat are generally far too expensive and the only other main source of protein is groundnuts. Cassava root and leaf are the staple foods for most rural and city dwellers. In the R. D. Congo as a whole the consumption of caterpillars is estimated to be 40% of total animal protein consumed. Malaisse & Parent (1980) analysed the nutritional value of 22 species of edible caterpillar and found the kcal/100 grams dry weight averaged 457 and crude protein content averaged 63.5%.

Quantities actually harvested from an area of savannah or forest vary greatly according to species and the prevalence of their food plants. It is estimated however that for Cirina forda an amount of 5kg. dry caterpillars can be produced per ha.Mopane worms in southern Africa are gathered and marketed commercially to the value of over 1 million Rand annually and in Malawi yields of 14.63kg/ha. have been recorded (Munthali & Mughogho 1992). Often sufficient quantities are found during the rain season for them to be sun dried and kept for use throughout the year or else transported live to the main markets. Kinshasa, for example, has a section where it is common to find a wide range of species offered for sale. One can even purchase dried caterpillars in London !

Species – Mainly species of Saturniidae (Emperor moths) e.g. Imbrasia ertli, Cirina forda but Notodontidae are also important e.g. Anaphe sp. A total of over 40 species are known to be eaten in Bas Congo.

Imbrasia ertli = (Diverse Emperor) Mvinsu in Ntandu dialect of Kikongo. (slide 2)

 Slide 2 Imbrasia ertli moth - an important species producing a much appreciated caterpillar in Bas Congo

A highly gregarious forest species which appears from December to January and is very much appreciated. The eggs are usually laid in groups on the leaves of Ricinodendron heudelotii, Petersianthus macrocarpus (African stinkwood), Funtumia africana (False rubber tree) orHolarrhena floribunda. Droppings found below a tree indicate the presence of this species and the tree may be marked by tying palm leaves around the trunk to claim ownership of the colony. Larvae always move and feed in close contact (slide 3,4). Initially larvae have long hairs (slide 5) but in the final instar when they are collected (slide 6) most of these are lost. Saturniidae normally moult up to 5 times. When moulting caterpillars first descend the trunk of the tree to between 1 and 2m above ground level (slide 7,8).

Slide 7 Close up of colony of Imbrasia ertli on the base of a Funtumia tree. The caterpillar descend from the foliage of the tree each time they moult. It is at this stage they are collected for eating

Normally the whole colony is taken and can either be eaten after roasting or boiling or else can be sun dried for later use.

Imbrasia  ertli caterpillars collected from the trunk of a tree when they descend to moult With the shortening of the forest fallow the food plants, particularly Petersianthus macrocarpus, have become less common and over collection of the caterpillar itself has reduced its numbers. 

Traditionally Ricinodendron heudelotii (slide 9) trees were planted in the villages in Bas Congo to attract this caterpillar. Providing a reasonable number of caterpillars are allowed to descend to the ground to pupate in the soil the moths will often lay their eggs on the same food plant, or on others nearby, so that a continual supply can be obtained.

Cirina forda = (Pallid emperor) Ngala (slide 10)

A gregarious, savannah species also appearing from December to January in Bas Congo. Again it is much sought after but has become difficult to find in some areas where it used to be common. This is primarily due to annual bush fires which destroy the pupae laid about 5cm underground. Only one host plant is known in Bas Congo, Crossopteryx febrifuga, the Ordeal tree (slide 11). Defoliation of the tree usually indicates the presence of this caterpillar (slide 12). A pyramid of eggs is laid on a twig and these hatch out and feed nearby (slide 13). Moulting takes place wherever the caterpillars happen to be, rather than in a group. The final instar is normally collected (slide 14) before the caterpillars fall to the ground and pupate just below the soil surface. Unless disturbed this species does not move far from the area the previous generation occupied. Thus, providing enough caterpillars are allowed to pupate and fire breaks are well maintained, the species can be reared annually on the same spot. If bush fires can be restricted to certain times of the year it has been shown that pupae are not so badly affected. Production of this species can easily amount to 5kg. dried caterpillars /ha. as the food plant is a very common savannah species in many areas of the province. It should be possible for this species to be reared as a compound species as the tree is fairly small, coppices well producing large amounts of fresh green foliage at the start of the rains. Gut contents have to be removed before cooking. This is done by slitting open the caterpillar and washing out the contents or by using a sharpened stick to push the caterpillar inside out.

Anaphesp. = (African silk worm) Nkankiti

A Notodontidae species, the larvae of which build a strong waterproof sack (slide 15) in which the colony live during the day, coming out to feed at night on various Bridelia species (B. micrantha, ferruginea and ripicola). Because of their high fat content they are particularly appreciated (slide 16). This species, though becoming difficult to find in Bas Congo, is widely distributed in the region. The food plant is common and it should be possible to increase production with the right management. The larvae are fried without removing the gut contents.

Conservation of species and food plants

It is mainly children who collect caterpillars, though I have often been aware, while walking in the bush, that most people keep a constant watch out for edible caterpillars. One species in particular is located when its droppings are seen among the debris on the ground.This has given rise to the Kongo proverb which says that “the death of the Kaba (a large green caterpillar, which is otherwise hard to see among the foliage) is caused by its own droppings.” (slide 17,18)

Frequently people will bring back young larvae and place them on trees near their homes where they can keep an eye on them. Many villages have a few Acacia auriculiformis trees planted nearby and these are used to rear the caterpillars of a number of species until they are ready to eat (slide 19). Some farmers have taken this a step further and allow a proportion of caterpillars to form cocoons and frequently, for certain species, the resulting moths will lay eggs on the same or nearby trees. One farmer purchased Cirina forda larvae in the local market, introduced them to an area of savannah with plenty of Crossopteryx febrifuga and has been able to harvest the caterpillars regularly. That is until this year, when unfortunately he became ill and while in hospital, the whole lot were stolen.

The development project I work with is involved in the conservation of some of the important species of edible caterpillar and their food plants. This involves :- 

1. Working out propagation methods for the food plants, particularly where caterpillarspecies are only found on one species of plant e.g. Cirina forda which feeds exclusively on Crossopteryx febrifuga in Bas Congo. 

2. Teaching farmers methods of conservation. To help villagers recognise the various species of caterpillars and their food plants an illustrated manual has been produced in both French and Kongo. A flip chart and poster (slide 20) has also been developed for use as an extension tool in village meetings. Traditionally people did not cut down trees when collecting caterpillars. Nor did they collect the pupae and they respected certain times for burning the savannah to minimize destruction of the pupae.

3. Identifying sites where caterpillars can be introduced and reared safely. These have to be safe from fire and theft. A forest fallow with plenty of beehives is a good site for rearing caterpillars (slide 21,22,23).

Preparation, storage, palatability

A good knowledge oflocal plants is vital when collecting caterpillars. The gut contents of some caterpillars have to be removed, particularly if they have been feeding on ‘toxic’ plants. This is particularly the case with Lobobunea phaedusa (the Blotched Emperor), which feeds on a wide range of plants. Caterpillars are either pushed inside out with a thin stick or punctured and the contents squeezed out. 

A number of caterpillars possess spines or long hairs which must be removed before eating. This is usually done by singeing them off on a hot metal sheet over the fire and is done before removing the gut contents. They are then either boiled or fried with peanut butter, mixed with cassava leaves, cooked with pumpkin and sesame seeds or simply fried with salt and a few hot peppers. The African silk moth larvae contain a good amount of fat so can be fried without additional oil.

Frequently, and especially if large quantities of caterpillars are harvested, they are dried out in the sun and stored for later use or sold in the local markets. One species, Minsangula, though not frequent is found in sackfulls.

Cultural aspects

Caterpillars are considered a luxury food on a par with the fruit of (Dacryodes edulis), the African pear, in Bas Congo. They usually bear the same name as the food tree on which they are most frequently found. This appears to be the case throughout Africa, wherever caterpillars are eaten.

Caterpillar species also enter into folk lore and are commonly invested with human characteristics. In Bas Congo a number of proverbs relate to caterpillars and their behaviour.

Conclusion

The eating of insects may appear novel or even repugnant yet insects represent an important high protein food for many rural families in Africa. There is potential for far greater production with minimum additionalinput of labour. Most edible caterpillars in Bas Congo live on forest trees and thus enhance the value of the traditional forest fallow. It has been shown that the combined output, annually, from beekeeping and the production of edible caterpillars from an area of forest can far exceed the value of the food crop that the forest was cut down for (Munthali & Mughogho 1992). In this connection the importance of the forest fallow should be re-emphasised because, in large parts of the humid tropics, it still represents the only practical method for replenishing soil fertility (Nye & Greenland 1960).

* Croft Cottage, Forneth, Blairgowrie, Perthshire PH10 6SW, Scotland 

Literature

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Gomez P.A., Halut R. and Colin A. (1961) Production des Proteins animales au Congo Belge. Bull. Ag. Congo Belge 52 (4) 689 

Latham P. (2001) Edible caterpillars and their food plants in Bas Congo, R.D. Congo. Forneth (U.K.), 41 p.

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Ramos-Elorduy, J. (1997) Insects: A sustainable source of food ? Ecology of Food and Nutrition 36 pp 247 - 276