''Gonometa postica'' ( Walker, 1855), known commonly as the African wild silk moth, burn worm, and brandwurm,Bause, T
Beautiful silk scarves from a nasty pest.
''The Namibian'' June 24, 2005. is a large species of African moth belonging to the family Lasiocampidae. The genus ''Gonometa'' boasts some very large moths and larvae; ''

Gonometa sjostedti ''Gonometa'' is a genus of moths in the family Lasiocampidae. The genus was erected by Francis Walker in 1855."''Gonomet ...

'' from Africa has a larva 16 centimeters long, for example. Most of the Lasiocampidae are highly sexually dimorphic. In ''G. postica'' the forewing of the male measures 21–25 mm and of the female 35–42 mm. ''Gonometa postica'' and ''

Argema mimosae ''Argema mimosae'', the African moon moth, is a giant silk moth of the family Saturniidae. Similar in appearance to the giant Madagascan moon moth ('' Argema mittrei''), but smaller, this moth can be found widely in Eastern Africa and more locall ...

'' cocoons are traditionally used as ankle rattles in southern Africa by San and Bantu tribes. They are filled with materials such as fine gravel, seeds, glass beads, broken sea shells, or pieces of ostrich eggshell. The species has become notable for producing a fine quality wild silk in its cocoon. The cocoons are harvested commercially in Namibia, Botswana, Kenya and South Africa, and the species also occurs in Zimbabwe and Mozambique. An Oxford University research team found that the cocoon surfaces are covered with

calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydrate ...

, hindering their commercial utilisation. They discovered and patented a method known as demineralizing using a warm solution of EDTA (ethylenediaminetetraacetic acid), softening the cocoons by dissolving the

sericin Sericin is a protein created by ''Bombyx mori'' (silkworms) in the production of silk. Silk is a fibre produced by the silkworm in production of its Pupa#Cocoon, cocoon. It consists mainly of two proteins, fibroin and sericin. Silk consists of ...

, permitting the silk to be unravelled with no appreciable loss of strength. Cocoons are also sexually dimorphic, with those of females being roughly twice the size of those of males, thus yielding more silk. Sex ratios in natural populations will clearly play a large role in the harvesting of cocoons.Veldtman, R., et al. (2002)
Variability in cocoon size in southern African wild silk moths: implications for sustainable harvesting.
''African Entomology'' 10(1) 127-36. The larvae are quite variable in their patterning and, like many of the genus, are covered in irritating setae, or hairs. The larva is black with lateral tufts of white, yellow or orange. It has been recorded feeding on ''

Acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...

'', '' Brachystegia'', '' Elephantorrhiza'', '' Pinus radiata'', and '' Julbernardia''. Another silk-producing member of the genus is ''

Gonometa rufobrunnea ''Gonometa'' is a genus of moths in the family Lasiocampidae. The genus was erected by Francis Walker (entomologist), Francis Walker in 1855.

'' ( Aurivillius, 1927), which feeds almost exclusively on ''

Colophospermum mopane ''Colophospermum mopane'', commonly called mopane, mopani, balsam tree, butterfly tree, or turpentine tree, is a tree in the legume family ( Fabaceae), that grows in hot, dry, low-lying areas, in elevation, in the far northern parts of southern ...

''.''Gonometa postica'': Kalahari Wild Silk.
Anthropological Entomology: Silk Textiles. Mississippi Entomological Museum.Fening, K. O., et al. (2010)
Effect of seasons and larval food plants on the quality of ''Gonometa postica'' cocoons.
''Phytoparasitica'' 38(2) 111-19. ''G. postica'' larvae and pupae are subject to

parasitism Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

and

Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...

, the most common

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

s being '' Palexorista'' species from the Tachinidae and ''Goryphus'' species from the Ichneumonidae.Fening, K. O., et al. (2008)
Parasitoids of the African wild silkmoth, ''Gonometa postica'' (Lepidoptera: Lasiocampidae) in the Mwingi forests, Kenya.
''Journal of Applied Entomology'' 133(6) 411-15. The cocoons have long been known to cause the death of cattle, antelope and other ruminants in the Kalahari. During drought periods, the cocoons are eaten, probably because they resemble acacia pods. The silk is indigestible and blocks the rumen of multiple-stomach animals, causing starvation.Bafana, B
Going wild for silk in Zimbabwe.
''New Agriculturist''. May, 2009. In Madagascar, wild silk has been harvested for centuries, and this expertise has been introduced to southern Africa. A feasibility study was funded by

Oxfam Oxfam is a British-founded confederation of 21 independent charitable organizations focusing on the alleviation of global poverty, founded in 1942 and led by Oxfam International. History Founded at 17 Broad Street, Oxford, as the Oxford Co ...

and the Namibian Ministry of Agriculture, and a pilot project was started in Leonardville. A number of other moth species suited to silk harvesting are '' Attacus atlas'', '' Antheraea paphia'', '' Antheraea pernyi'', '' Cricula andrei'', and ''

Samia canningi ''Samia canningi'' is a moth of the family Saturniidae. It is found in south-eastern Asia and China. The wingspan is . The larvae mainly feed on '' Ailanthus altissima'', '' Prunus laurocerasus'', ''Ligustrum'' and '' Syringa'' species. Pupati ...

''. ''Gonometa'' fibroin is rich in basic amino acids, making it a potentially useful biomaterial in cell and tissue culture.Mhuka, V., et al. (2013)
Chemical, structural and thermal properties of ''Gonometa postica'' silk fibroin, a potential biomaterial.
''Int J Biol Macromol.'' 52 305-11.

References

External links

University of Oxford. 20 May 2011.
Setae of Larva.
GEO-Reisecommunity.
Cocoon of ''Gonometa postica'''Nonmulberry silk biopolymers'
{{Taxonbar, from=Q5438065 Gonometa Silk production Moths described in 1855 Moths of Africa