MORPHOLOGY AND LIFE CYCLE OF SILKWORMS AND THEIR HOST PLANTS

1. MORPHOLOGY AND LIFE
CYCLE OF SILKWORMS AND
THEIR HOST PLANTS
By,
Nayana, B. P.
Msc. (Agri.)
SRF
UAHS, Shivamogga

2. Classifications
1. Classification based on voltinism:
• Voltinism refers to the number of broods raised per year.
• Based on voltinism, three kinds of races are recognized in mulberry
silkworm, Univoltines, bivoltines and multivoltines.
2. Classification based on moultinism/ No. of larval moults :
• Number of moults during the life cycle is a hereditary character
determined by Mendelian genes.
• On the basis of the number of moults which they undergo during
larval life, B. mori is divided into three races – tri moulters, tetra
moulters and penta moulters.
• Most of the commercially exploited races are tetra-moulters with five
larval instars.

3. 3. Classification based on geographical distribution :
Based on their place of origin, B. mori is classified into Chinese, Japanese,
European and Indian races.
The races can be distinguished from one another on the basis of
1. Morphological characters of egg, larva, cocoon and adult.
2. Biological characters like duration of life cycle, diapause, number of larval
moults and resistance to diseases as well as other environmental factors and
commercial characters like length of filament, denier, defective cocoon
percentage, reelability etc.
4. Classification based on genetic nature:
Based on genetic nature, silkworm races are classified as pure races and hybrids.
5. Classification based on Host Plants:
1. Mulberry silkworm
2. Non – Mulberry silkworms

4. Commonname Scientificname family Main host
Mulbery silk worm Bombyxmori Bombycidae Mulberry
Eri silk worm
(domesticated)
Phylosamia ricini Saturnidae Castor
Eri silk worm (wild) Pylosamia synthia Saturnidae Castor
Chinesstassar silk
worm (wild)
Antheraea perni Saturnidae Oak& otherallied
species
Japanesstassar silk
worm(wild)
Antheraea
yamamai
Saturnidae Oak& otherallied
species
Indian tassarsilk
worm (wild)
Antheraea mylitta Saturnidae Terminalia
Muga silk worm Antheraea assama Saturnidae Som(michilli
s bombicina)

6. 1. Mulberry silkworm, Bombyx mori L.
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Bombycidae
Genus: Bombyx
Species: mori
Binomial name
Bombyxmori
Host plant: Mulberry
It is the domesticated worm – 4000 years.

8. Eggs
• Eggs are placed in clusters on the leaves.
• The female covers the eggs by a gelatinous secretion which
glues them to the surface of the leaves.
• The eggs are small, oval and usually slightly yellowish in
colour.
• The egg contains a good amount of yolk and is covered by a
smooth hard chitinous shell.
• After laying the eggs the female moth does not take any food
and dies within 4-5 days.

10. • Larva is domesticated, glabrous, elongate
• Crescent shaped markings in second abdominal
segment
• Star shaped marking in fifth abdominal segment
• Medio-dorsal caudal horn on eighth abdominal
segment.
• It forms dense cocoons
• The larva is Monophagous and feeds on mulberry,
Morus indica, Morus alba, Morus rubra, Morus nigra,
etc

19. Cocoons vary
• In shape (spherical, oval, peanut, pointed and
conical) and
• Colour (white, yellow, pink, golden yellow etc.)
according to race.
• The cocoon composes of a single continuous
reelable thread ranging from 500- 1500 meters in
length.
• Pupa is obtect

21. • Moths are
– milky white in colour,
– medium sized,
– with smoky wavy lines on white coloured fore and
hind wings.
• The apex of the forewing is slightly elongated
and curved.
• Frenulum is almost atrophied or absent.
• Maxillary palpi and tymphanal organs are absent
• Antennae are bipectinate

27. 1. Eri silkworm – Samia cynthia ricini Boised.
(Saturniidae: Lepidoptera) Syn. Philosamia ricini
 It is a non-mulberry, multivoltine, domestic moth,
reared indoor.
 Susceptible to unhygenic and poor environmental
conditions
Non mulberry silkworms

28. • The female starts laying egg and
continue up to 3 days.
• Fecundity: 120-200 eggs
• Eggs colour- White
• Incubation period : 7-10 days
• Larvae are
– domesticated,
– polymorphic (white, yellow, zebra
and bluish),
– robust and
– possess scoli.
• Larval period :17-25 days

29.  Larva forms creamy white or darkish brown,
 Elongated and
 Soft cocoons with an opening at one end, (open end cocoon)
 Eri cocoons are stalkless, flossy, white or brick red in colour
 The silk is non-reelable. So it is not in one single strand
i.e., not continuous.
 Pupa is obtect.
 Pupal Period:
10-12 days

30.  Moths are brownish black in colour, large sized with
about 8-10 cm wing expansion.
 Wings are specked with triangular eyespot almost
near its centre, with characteristic brown lines.
 Antennae are bipectinate.
 Adult Longevity: 6-7 days
 Total Lifecycle: 50-60 days

32. The larva is polyphagus and feeds on
Castor – Ricinus communis
Kesseru - Heteropanax fragrans
Tapioca - Manihot utilissima
Papaya - Carica papaya
Champa – Plumeria acutifolia
Barkesseru - Alianthus spp.
Payam – Evodia flaxinifolia.

33. Castor – Ricinus communis

34. Tapioca - Manihot utilissim

35. Kesseru - Heteropanax fragrans

36. Barkesseru - Alianthus spp.

37. Champa – Plumeria acutifolia

38. 2. Tasar silkworm – Antheraea mylitta Drury
• The tasar silkworm has two varieties viz. tropical and temperate.
• Tropical tasar silkworm Antheraea mylitta Drury is
commercially exploited in India for production of vanya silk
• A large number of poor families depend on tasar culture for their
livelihood.
• Tasar silk displays a higher value of air permeability as
compared to mulberry silk

39. • Eggs are oval,
– ellipsoidal,
– slightly flat and
– bilaterally symmetrical
in shape
• Colour - brown at the time of oviposition.
• Fecundity: 180-200
• Incubation period: 8-10 days

40. • The larva is robust and posses scoli and is
semi-domesticated.
• The newly hatched larva - dark brownish or dull
yellow in colour
• The colour of fifth instar larva - greenish in colour
• Larval period – 35-70 days.
• It forms dense, firm cocoons.

42. The filament is reelable and
measures around 500-1300
meters.
Black or brown coloured
prominent peduncle and ring.
Cocoon color - silver grey (white),
suede (grey), daffodil (yellow)
Pupal Period: 25-50
Pupa is obtect

43.  Moths are large in size with 20 cm wing expansion.
 The wings of males vary from brown to dark grey in color, while in
females vary from yellowish-grey to brownish shades.
Wings are speckled with transparent circular eye-spot near the
centre.
 Antennae are bipectinate.
Adult Longevity: 8-10 days; Total Lifecycle: 74-96 days

45. The larvae are polyphagus and mainly feeds on –
Asan – Terminalia tomentosa
Arjun – Terminalia arjuna
Sal – Shorea robusta
Ber – Zizyphus zuzuba
Sidha - Lagerstroemia pariviflora
Kumbi- Careya arborea
Jamun – Syzygium cumini
Teak - Tectona grandis
Australian babul – Acacia auriculeiformis

46. Terminalia tomentosa

48. Shorea robusta

49. Zizyphus zuzuba

50. Lagerstroemia pariviflora

51. Syzygium cumini

52. Tectona grandis

53. Acacia auriculeiformis

54. 3. Muga silkworm–Antheraea assamensis Westwood
 Muga silkworm is endemic to Assam and adjoining areas in North-
Eastern India, and naturally produces golden silk.
 Ethnics and tribal groups have produced muga silk.
 Muga silkworms are mostly wild unlike the mulberry silkworm
 Muga silkworm occurs in the Brahmaputra valley in Assam, East,
West and South Garo hills of Meghalaya, Nagaland, Lohit and
Dibang valleys, Arunachal Pradesh, Manipur and West Bengal

55. • Eggs are oval,
– ellipsoidal,
– dorsoventrally flattened
– bilaterally symmetrical
in shape
• Colour - brownish grey at the time of
oviposition.
• Fecundity: 180-200
• Incubation period: 8-10 days

56. • Larvae are green in color and semi domesticated and
reared mostly in Assam.
• Larval period – 35-70 days.
• Cocoon color varies from golden to glossy white with
rudimentary peduncle, hence called golden cocoon.
• The filament is reelable.
• Pupa is obtect.

57. • Moths are large with 25cm wing
expansion.
• The wings are brown with a
transparent eyespot in the centre.
• Antennae are bipectinate.

59. Som – Machilus bomycina
Host Plants

60. Solu - Litsaea citrata