Silkworm

1. Lecture 8
Types of silkworm - Mulberry silkworm – origin –
classification based on voltinism, moultinism,
geographical distribution & genetic nature –
Characters of multivoltine races, bivoltine races,
cross breeds and bivoltine hybrids – double
hybrids– suitability for rearing in different seasons

2. History of silk worm
• Silkworm industry originated in China about 3000 B.C.
• Chinese Princess Hsi-ling-chi – serendipity
• Silk = most elegant textile in world
– natural sheen,
– easily mix with dyes,
– high absorbance,
– light weight,
– soft touch and
– high durability
• “Queen of Textiles”.
• India - 5 types of commercial silks viz., mulberry,
tropical tasar, oak tasar, eri and muga.

3. Systematic position
Mulberry silkworm
• Scientific name : Bombyx mori
• Family : Bombycidae
• Super family : Bombycoidea
• Order : Lepidoptera

4. Types of Silk
Type of silk Distribution Type of Silk insects
Mulberry Karnataka, Andhra Pradesh,
Tamil Nadu, Kerala,
Maharashtra,West Bengal and
J&K
Bombyx mori (Bombycidae)
Tasar
(Undergoes
pupal diapause)
Jharkhand, Bihar,
Chhattisgarh, Madhya
Pradesh, Orissa and West
Bengal & Andhra Pradesh
Tropical tassar (India)
Antheraea mylitta (Saturniidae)
Temperate Tassar
Antheraea proylei (India)
Antheraea yamamai (Japan)
Antheraea pernyi (China & USSR)
Eri Assam, Bihar, Manipur,
Meghalaya, Nagaland & West
Bengal
Attacus (=Philosamia) ricini
(Saturniidae)
Muga
(only in India)
only in Assam (pride of
Assam), parts of Tripura
Antheraea assamensis
(Saturniidae)

5. Types of silk worm (larva)
Mulberry silk worm Tassar silk worm
Eri silk worm Muga silk worm

6. Types of Silk, food plants & color of
silk
Type of silk Food plants Colour of silk produced
Mulberry Morus alba (Mulberry) Creamy white
Tasar (Undergoes
pupal diapause)
Terminalia arjuna (Arjun),
Terminalia tomentosa (Asan),
Zizyphus jujuba (Plum),
Shorea robusta (Sal),
Oak
coppery colour – non-
reelable only spun.
Furnishings & interiors
Eri Ricinus communis (castor) Brick-red silk
Muga
(only in India)
Tetranthera monopetala
(Som),
Michalia oblonga (champa),
Litsaea polyantha
(Moyankuri)
Golden colour, costly

7. Morus alba
Ricinus communis
Zizyphus jujuba
Tetranthera monopetala

8. Silk worm life cycle
• 4 stages
• Eggs  baby worms =
Black worm/ ant/ kego
• I & II instar feed - fresh
succulent mulberry leaves
until they reach III instar.
• III instar  whole branch
of mulberry leaves fed to
worms
• Silkworms feed until they enter cocoon (Pupal) stage
• While spinning cocoons, worms produce jelly-like substance in their
silk glands, which hardens upon contact with air and spin cocoons
around them
• After 4-5 days in a warm, dry place, cocoons are ready to be
unwound.
• Total life cycle = 25 to 35 days (depending upon race and climatic
condition)

9. CLASSIFICATION OF MULBERRY
SILKWORM
• Based on voltinism
– Univoltines, bivoltines and multivoltines
• Based on moultinism
– tri moulters, tetra moulters and penta moulters.
• Based on geographical distribution
– Chinese, Japanese, European and Indian races
• Based on genetic nature
– pure races and hybrids

10. Differences between Uni- Bi- &
Multivoltine races
Races Univoltine Bivoltine Multivoltine
Generation/ year One Two > 2
Larval duration relatively longer longer Short
larval weight higher Highest lower
Cocoon weight heavy Heavier Less heavy
Denier > 2.3
Tolerance Not tolerant to
Higher
temperatures
tolerate
environmental
fluctuations
Well adapted to
tropical conditions
Races European races Japanese and Chinese
races
Indian races
Diapause lay only diapausing
eggs
Lay diapausing eggs &
non diapausing eggs
Lay non-diapausing
eggs
Commercial value commercially
superior
commercially
superior
Poor quality

11. Multivoltine X Bivoltine (cross breeds)
Parameter Native pure
lines
Cross breed
PMxNB4D2
Bivoltine
hybrid
CSR2xCSR4
Cocoon weight (g) 1 1.7 1.9
Shell weight (g) 10 17 24
Filament length (m) 300-400 730 1150
Neatness (points) Less 82 94
Renditta 10-15 9 5
Renditta
number of kilograms of fresh cocoons required to produce
one kilogram of raw silk

12. Silk worm larva

13. Silk worm pupa

14. Silk worm facts…
• Female silk worm moth lays - 300 to
500 eggs
• After 5-6 moults, the silkworm
extrudes a silk fibre from its salivary
gland (swinging itself from side to
side in 8 shape) and forms silken
coccon.
• Silkworm spins ~2 kms of filament in
2/3 days.
• ~2,500 silkworms = 1 pound (0.45 kg)
of raw silk
• Intact cocoons  boiled to kill the
silkworm pupa
• One cocoon  1,000 yards of silk
filament (910 metres)
• Silk at this stage = raw silk
• What is meant by ahimsa silk??