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IN AN AREA the size of this page, 50 moths deposit more than 20,000
eggs, each about the size of a pinhead. From each egg emerges a larva that
will eat 50,000 times its initial weight in plant material. Within just
three weeks, more than half a tonne of carefully nurtured leaves are transformed
into a mass of ugly, fat, hairless creatures, each as much as 8 centimetres
long.

Less than a decade ago, more than half a million farm families in northeast
Thailand faced this multitude at least once a year. But the insects were
not an enemy. Quite the opposite. If all goes well, each batch of larvae
transforms otherwise valueless mulberry leaves into a few kilograms of that
most luxurious and sensuous of natural fibres – silk. But one in three families
has now given up the traditional culture of silkworms.

The loss of a large part of Thailand’s silk industry is a direct result
of the European Community’s Common Agricultural Policy. The CAP subsidises
European farmers to the tune of $10 billion a year, a practice that often
provokes controversy. But attention rarely focuses on the ways in which
the policy affects farmers in developing countries. Subsidies in the mid-1970s
kept the price of cereals in Europe artificially high, so livestock farmers
in the Community turned to cassava as feed for their animals. With encouragement
from the EEC, many farmers in Thailand abandoned their production of silk
and turned their attention to cassava. Now changes to the CAP, which could
reduce the demand for cassava, threaten the livelihoods of many of Thailand’s
poorest farmers. Ironically, these changes might revive interest in producing
silk.

The mulberry silkmoth, Bombyx mori, is unique among insects in that,
instead of being ignored or despised, it forms the basis of an industry
worth billions of dollars a year . Thailand has probably produced its own
silk for more than 1000 years. Despite this, the country has always preferred
to import from its neighbours. When Japan modernised its silk industry late
in the 19th century, Thailand’s silk producers suffered badly. Most abandoned
attempts at commercial production and made just enough raw silk to meet
their own needs. In the first decade of this century, the government of
Siam, as it was then, tried hard to revitalise the traditional silk industry,
but to little effect. By 1947, when an American called Jim Thompson decided
to set up a silk business in Thailand, the few commercial weaving families
that remained were learning more profitable trades. Yet, within 10 years,
Thompson had transformed their fortunes and developed an industry ranked
as one of the great success stories of postwar Asia.

The industry continues to grow, but it is no longer based on home-grown
silk. Exports of fabric have almost doubled in the past five years and ‘invisible’
exports, the sales of material and silk goods to tourists, have probably
grown even more rapidly. Unfortunately, domestic supplies of raw silk have
not kept pace; imports of silk yarn doubled in a single year in 1987. In
the northeast of the country, which produces 95 per cent of Thailand’s raw
silk, the area under mulberry has shrunk from almost 60,000 hectares to
less than 40,000 hectares since the mid-1970s. Despite the growing market
and high prices for Thai silk, many farmers have found that silk is unprofitable.
Traditional silk farmers earn barely half as much as a farm labourer. Yet
there are still more than 350,000 families in the northeast producing traditional
Thai silk. They persist because silk is an integral part of a traditional
system of agriculture that is finely adapted to the local economy and environment.

Much of northeast Thailand is unsuitable for farming and so the region
is poor. Most of the land that can be cultivated is devoted to paddy, but
produces low yields. In the upland areas the soils are acid and contain
little organic material: they are often waterlogged in the rainy season,
but during the seasonal drought, they dry out to a considerable depth.

Farmers in the northeast have always concentrated on producing enough
rice to support their families. They grow cash crops to supplement their
income, but rice always takes priority.

For more than 1000 years, silk farming was a part of this agricultural
system. Mulberry is a drought-resistant, perennial crop which brought in
cash from marginal land that might otherwise be worthless. Traditional silk
farming requires little equipment and little money; there are virtually
no financial risks. In the unlikely event of the market for raw silk disappearing,
the silk is simply used at home. Even if the crop fails, only the labour
has been wasted (dead larvae and wastes from the rearing beds are made into
compost and returned to the mulberry plots). Silk production is certainly
labour-intensive and the returns are low, but the work is light and most
of the activity takes place in the home.

The traditional way of life in the northeast changed in the 1970s, when
European farmers began to import cassava to feed their livestock. Cassava
is extremely resistant to drought and the expanding market encouraged farmers
to grow it as a cash crop in many difficult regions, including northeast
Thailand. Cassava performed so well there that many farmers increased their
incomes fivefold, while still having time toearn money from other types
of jobs. Against such powerful economic arguments, only those women who
weredetermined to maintain the tradition of silk farming coulddissuade their
husbands from uprooting all the mulberry tomake room for cassava.

Now, however, both the Thai government and the European Commission are
concerned about the decline in silk production. If Europe succeeds in bringing
the CAP more in line with world markets, demand for Thailand’s cassava could
disappear. More than 60 per cent of the cassava is produced in the northeast.
The government fears that the loss of income could force people to head
for the cities to look for work or turn to slash-and-burn agriculture, growing
unsustainable cash crops. It is also afraid of social unrest in the areas
bordered by Laos and Cambodia. The European Commission is anxious to help
the government in a programme of diversification, to reduce people’s dependence
on cassava. One of the options they are considering is silk farming.

The programme faces a huge obstacle: in the absence of a proven package
of crops that produces better returns than cassava, farmers will not diversify
unless, and until, the demand for cassava collapses. Without more investment,
the areas currently under cassava will support few other cash crops. Those
crops that might produce equivalent returns are generally perennials, which
take time to become established; during this period farmers would lose the
incomes they could have had from cassava. Several projects have shown that
farmers in the northeast can earn a decent income from silk – but only if
they invest in expensive modern technologyand imported silkworms. Few farmers
are willing to takesuch a risk. Yet, much greater benefits would come fromimprovements
based on the hardy native silkworms, improvedmulberry plants and appropriate
technology.

Thailand’s silkworms are not the same as those that grow in the cooler
climates of Japan and China, where the silk industry is more advanced. In
Japan and China silkworms produceone or two generations each year. The most
important characteristic of these ‘monovoltine’ and ‘bivoltine’ races is
that they produce large cocoons spun from a continuous filament of silk
more than a kilometre long. Another valuable feature of these races is that
the female moths can be induced to lay eggs which enter diapause, a state
of suspended development. Dormant eggs will keep for several months, but
they can be treated at any time to induce hatching in accordance with a
production schedule.

The monovoltine and bivoltine races of silkworms do not thrive in tropical
countries like Thailand, where they are beset by viral and bacterial diseases.
The race adapted to tropical conditions produces young continuously, it
is ‘polyvoltine’; it develops fast and can produce at least 10 generations
a year. But polyvoltine cocoons are usually small and poorly shaped, and
the eggs must be allowed to hatch within about two weeks or they will die.

All races of the mulberry silkworm convert leaves into silk with the
same efficiency – a meagre 1 per cent at most. You cannot increase productivity
as you can with cattle, for example, by diverting food away from growth
to the production of the desired commodity, because silkworms produce silk
after they have stopped growing and are preparing to pupate. However, if
the bivoltine and monovoltine races receive enough mulberry leaves, they
produce cocoons large enough to process by machine. So these races of silkworm
can support a capital-intensive, factory-based industry in which farmers
produce cocoons as a cash crop which they sell to the yarn producers. Moreover,
because most automatic reeling machines are designed to process cocoons
that have been stifled and dried, farmers can store their produce until
they fetch a good price.

These machines cannot process small cocoons, and so farmers rearing
native polyvoltine silkworms have no regular market for their produce. Their
only option is to reel the cocoons by hand to produce either raw silk or
woven material for sale.

This is a big problem because only ‘green’ cocoons (unstifled cocoons
containing live pupae) are suitable for hand reeling. The stifling treatment
damages the silk filaments and makes the cocoons much more difficult to
unwind. Hand reeling requires skill and patience; even experienced workers
rarely produce more than 300 grams of raw silk a day. With less than 10
days available before the moths emerge from the green cocoons and ruin them,
a farmer who produces more than about 40 000 polyvoltine cocoons (yielding
3 kilograms of raw silk) in any rearing cycle is likely to run out of time.
This limits the scale of any enterprise based on polyvoltine silkworms.
The average yield of raw silk in Thailand is 26 kilograms per hectare, compared
with 80 kilograms in Korea and between 90 and 125 kilograms in Japan.

The development of full-time commercial sericulture could increase farm
incomes in the northeast, but previous attempts to promote bivoltine silkworms
have met with patchy success. To reduce imports of warp, the Thai government
has actively encouraged the production of bivoltine cocoons for the past
20 years. The government carried out research with Japanese scientists for
almost a decade, and also introduced a system in which farmers sold stifled
cocoons to the reelers at a subsidised price. In the late 1970s and early
1980s the Public Welfare Department supported the development of bivoltine
sericulture in new settlements in the northeast, with support from USAID,
the US Agency for International Development.

These programmes succeeded to a degree: production of warp increased
rapidly, reaching 57 tonnes a year in 1987. But the increase was almost
entirely the result of expansion of large private businesses in the more
prosperous northern and central plains regions of Thailand. Mulberry grows
better in these regions, which have better soils and regular rain. The cooler
climate is more suitable for rearing bivoltine silkworms. Even so, the mulberry
plots need irrigation and, despite specially constructed rearing sheds,
some operations lost a third or more of their silkworms to viral diseases.
Among the settlements in the northeast involved in the programme set up
by the Public Welfare Department and USAID, production reached only 18 per
cent of the target in 1982 and was falling. By 1988, only one of the original
10 settlements was still rearing silkworms on a large scale, although in
that one village the project was so successful that families were earning
more than twice the national average.

Commercial silk farming with bivoltine silkworms is a capital-intensive
and comparatively high-risk venture. It hardly fits in with the social and
economic conditions in northeast Thailand. More important, perhaps, is the
fact that no one has paid enough attention to the implications of promoting
bivoltine sericulture at the expense of the traditional system. The commercial
hand weaving businesses, which form the hub of the modern Thai silk industry,
use bivoltine yarn only for the warp of the cloth. High-quality furnishing
fabrics use the coarser grades of hand-reeled silk for both warp and weft,
and no effective substitutes have yet been found. Some marketing specialists
are concerned that the European Commission, the Thai government and even
some weavers are losing sight of the fact that the country’s modern silk
industry is built on the unique qualities of the traditional product. These
ensure Thai silk a place in the international market despite fierce competition
from China and India. The only way to preserve these qualities is to make
good the shortfall in hand-reeled raw silk.

NEW RETURNS FROM OLD WAYS

The challenge is to find a way of increasing the returns from traditional
silk farming. Higher prices for the finished articles might damage sales,
and the increased takings might not trickle down to the farmers. The redistribution
of profits within the industry, so that the farmers earn more and the traders
less, might prove more effective but would be difficult to administer. The
most attractive option is to make the traditional system more productive
by solving the technical problems that limit it.

Provided there are enough silkworms to transform leaves into silk, the
output of thread is determined by the input of mulberry leaves and the amount
of labour available to tend the silkworms and reel the cocoons. Except during
times of planting and harvesting the rice crop, an estimated 70 per cent
of the rural workforce is underemployed or unemployed. There should be no
shortage of labour, provided silk farming can be made profitable enough
to warrant hiring workers. The main constraints are the mulberries and the
silkworms – growing enough mulberry to feed the industry and keeping enough
silkworms alive to produce the silk.

Accurate measures of the productivity of mulberry and the survival of
silkworms are hard to come by. But combining government statistics with
information I collected during visits to silk farms in 1988, I estimate
that the average yield of mulberry in the northeast is around 5 tonnes per
hectare, yielding an average of 25 kilograms of silk – a conversion efficiency
of about 0.5 per cent. Increasing these figures to 7.5 tonnes per hectare
and 0.67 per cent would double the output of silk. These are realistic targets.
Mulberry can yield 30 tonnes per hectare in good, irrigated soils, and commercial
silk farmers rearing the vulnerable bivoltine silkworms in Thailand routinely
achieve conversion efficiencies of 0.8 per cent.

Capital-intensive systems of farming are unlikely to succeed in the
northeast, but if the farmers can reach these more modest targets cheaply,
the benefits to the region and to the country would be enormous. The extra
raw silk would be worth at least Pounds sterling 10 million a year. Twenty
thousand hand reelers would have relatively well-paid work all year round.
The silkworm rearers would earn more than they can from cassava and still
have time to grow rice if they wish to.

The surest way to increase silk production in northeast Thailand is
to identify the causes of poor productivity and to remove them. Unfortunately,
the European Commission is concentrating on administration and marketing,
instead of on the biological problems facing the industry. The commission
intends to spend Pounds sterling 8 million on the industry in the next five
years, but none on research.

The Thai Department of Agriculture is aware of the industry’s potential,
but its Sericulture Research Institute is too poor to investigate it. Programmes
of silk farming have a tradition of failure in northeast Thailand. So it
is ironic that while Europe is happy to pay for promoting the industry in
the region, it hesitates to pay for research that would ensure its investment
is not wasted.

FROM TREES TO SILK TIES: THE INSECT TRANSFORMERS

THE technology of silkmaking seems simple, but the fact that China enjoyed
a world monopoly on silk for 3000 years suggests that considerable research
and development must have gone into it. China held on to its secret despite
exporting fabrics to countries that had their own wild silk moths.

Eventually, the importers resorted to industrial espionage. Japan acquired
the technology by force in the 3rd century, by capturing four Chinese girls
and a supply of silkworm eggs. The Western superpowers were more subtle.
In AD 552, two Persian monks (agents of the Emperor Justinian) studied the
techniques during a pilgrimage through China and succeeded in smuggling
eggs to Constantinople inside their hollow pilgrim canes. Even today, China
dominates the export market for silk, which is worth more than a billion
dollars a year.

The silkworm is little more than a biotransformer: it converts chemical
precursors in the mulberry leaves into the protein fibroin and a gummy substance,
sericin, which binds the cocoon together. When this mixture leaves the silk
glands it is transparent and viscous, like glue. The full-grown larva begins
to build its cocoon by forcing some of this mixture through the spinneret
at the tip of its head and depositing it on a suitable surface.

By moving its head from side to side, the larva draws the mixture into
a continuous filament which is laid in a series of figures of eight to form
the walls of the cocoon. The act of drawing the mixture produces the silk
filament; the sericin then sets hard and binds the layers together.

Although damaged cocoons can be used to produce ‘spun silk’, only whole
cocoons, unpierced by emerging adult moths, can be reeled to produce true
silk. The only way to preserve the cocoons is to kill the pupae. The cycle
of biotransformation does not stop at this stage, however: each pair of
moths can produce several hundred eggs, and small batches of cocoons are
set aside as foundation stocks for the next generation of silkworms. The
remainder are either reeled within a few days, or are stifled and stored
or sold to the threadmakers.

The process of reeling begins by dissolving the sericin to loosen the
layers of filament. The traditional method is to place a handful of cocoons
in a basin of nearly boiling water set over an open fire. As soon as the
cocoons begin to soften, slight abrasion from a stick or brush finds the
outer end of the filaments, which are jerked until a single filament is
running from each cocoon. Each single filament (a bave) is too fine to be
of any commercial use – a single bave stretching from London to New York
would weigh just 1.5 kilograms.

Cocoons reeled together in hot water, while the sericin is still soft
and sticky, form what appears to be a single thread. The next step is to
draw the filaments from a number of cocoons, depending upon the required
thickness of thread, through a ‘croisure’, a system of small pulleys arranged
so that the thread is crossed with itself. This binds the filaments together
and removes surplus water. Each time a cocoon drops from the bundle, because
the thread breaks or because its silk is exhausted, another must be substituted
at once to maintain the thickness of the thread.

Silk yarn comes in two types with different functions. Warp yarn, which
provides the threads running the length of the material, must comply with
stringent specifications relating to length, uniformity of thickness, smoothness
and absence of breaks. Weft yarn, running the width of the cloth, does not
have to meet such exacting standards; indeed, some ‘faults’ are valued because
they give the finished material a special texture. However, most modern
power looms can only use silk yarn of an even and specified thickness. For
this reason, almost all reeling machines incorporate automatic devices that
control the thickness of the thread. Moreover, the silk is usually ‘thrown’
– twisted together with other silk threads to form a multi-thread yarn –
to give the yarn extra strength. Although a variety of thrown yarns can
be produced, the mechanical limitations of the looms tend to result in rather
standardised fabrics.

Hand-reeled raw silk is inevitably of uneven thickness; it cannot be
machine thrown and it is generally unsuitable for power looms. Paradoxically,
it is this inherent technical inferiority which gives Thai silk its characteristic
appearance and appeal. Traditional Thai silk weavers use native yarn for
both warp and weft, so the cloth is usually available only in the comparatively
short lengths intended for sarongs, generally less than 2 metres. The modern
Thai silk industry is based on hand-weaving using imported thrown yarn as
warp but home grown hand-reeled yarn as weft. This can produce a fabric
with an attractive, uneven texture and a brilliant lustre.

Hand-weaving is also the only way to produce silk furnishing fabrics
of high quality. Mechanised Jacquard looms can weave only 11 colours and
they cannot incorporate fragile gold threads. The richly decorated furnishings
of Versailles and Fontainebleau have more than 100 colours woven into them.
Hand-weaving also allows greater control and so it can produce more sumptuous
and unusual fabrics than a power loom.

Dr Ashley Morton recently wrote a report on silk farming for the Royal
Thai Government on behalf of the British Council. He was also a member of
the team that designed the European Commission’s sericulture project in
Thailand.