silkworm rearing plan , rearing house plan and equipments

1. By,
Nayana, B. P.
Msc. (Agri.)
SRF
UAHS, Shivamogga

2. • The rearing of the mulberry silkworms is fully domesticated.
• A silkworm-rearing house is the place where the silkworms
are reared to produce cocoons.
• The cocoon quality and yield are adversely affected if the
optimal environmental conditions i.e. temperature, relative
humidity, ventilation, illumination, hygiene, etc. are not
provided to the silkworms.
• The rearing house should be rationally designed in order to
keep the micro-climatic and environmental conditions for
rapid and healthy growth of the silkworms.
• It should, therefore, have facilities for creation and
maintenance of the optimal environmental conditions inside
the silkworm-rearing house.
• The rearing house should also provide sufficient space and
healthy environment for the workers attending the silkworm
rearing.

3. Optimal Environmental Conditions for Silkworms
• The optimum rearing temperature and relative
humidity for different stages of the silkworms
are as follows :

4. • When the temperature and relative humidity inside the
rearing house are below optimum conditions, they are
artificially raised through charcoal or electric heaters and
running humidifiers.
• When the rearing room temperature and relative
humidity are above the optimum conditions,
arrangements for natural cooling through good
ventilation or forced cooling through wet curtains on
windows, air coolers or air conditioner should be made
besides covering the roof with mats made up of coconut
fronds, grass etc.

5. LIGHT OR ILLUMINATION
• Young Silkworms prefer dark or dim light [15-30 lux].
• Light intensity influences the even distribution of the
larvae in the rearing bed.
• Silkworms are crowded in dark place in the rearing bed.
VENTILATION
• A silkworm rearing house should be well ventilated.
• Poor ventilation leads to humidity built up and
accumulation of gases like carbon monoxide, carbon
dioxide, ammonia, etc., which adversely affect the growth
of silkworms and make them susceptible to diseases

6. Rearing Bed Area Requirement for Silkworms
• The rearing bed area required for different races of the
silkworms during different stages of growth is given
below for 100 Dfls (2 Boxes) resulting in
approximately 40,000 larvae.
• Rearing bed area required for silkworms during
different stages for 40000 larvae

7. Young Age Silkworm Rearing House
• The Young age silkworm rearing houses are often called
as Chawki Rearing Centre (CRC).
• Adequate care in terms of temperature, relative humidity
and hygienic conditions should be provided to young
silkworms for their good and healthy growth.
• A CRC for brushing 5000-6000 dfls per batch consists of
a rearing hall of 30' x 30', leaf storage room of 10 ' x 20‘
and ante-room of 10' x 10' size.
• Adequate ventilation in the rearing hall is recommended.
A continuous water channel inside the rearing hall along
the walls helps in keeping the ants away from silkworms
and also maintaining the humidity.

8. • The windows should be fitted with wire mesh to avoid
entry of uzi fly.
• The ceiling should be kept at 9'-10' from floor.
• In case of more roof height a false ceiling at 8' to 9'
from floor helps in reducing the volume of air in the
rearing hall so that required temperature and humidity
can be maintained conveniently.

10. Late Age Silkworm Rearing House
1. The silkworm rearing house should be located on an
elevated place to avoid moisture migration from floor to
rearing house, provide good cross ventilation, facilitate
drainage of the water at the time of cleaning and
disinfection.
2. The rearing house should be north facing i.e., the windows
face north and south. This will avoid direct entry of the
sunlight into the rearing house.
3. Ventilators should be provided above and below the
windows for air circulation inside the rearing house.
4. The rearing house should have cement flooring for
maintaining hygiene.

11. 5. A 10-15 cm deep channel inside all around the rearing hall
should be provided to prevent entry of ants in the rearing
area and also to drain out water at the time of cleaning and
disinfection.
During summer, the water in channel helps in increasing the
humidity and cooling the air entering in through the lower
ventilators.
6. The roof of the house should be of either Asbestos sheets or
RCC to avoid entry of the Uzi-fly.
In hot regions, coconut fronds or straw should be placed over
the roof to avoid heat radiations during day time.
A false ceiling of plywood or thermocol sheet is also
effective in reducing the solar radiation from roof.

12. The minimum width of a rearing house for late age
rearing should be 5.5 m (18'). The length of the rearing
house can be calculated as follows:

13. Late Age Silkworm Rearing House

14. 1. The wall height in a rearing house should be minimum 10' on
the sides and 14' at the center.
2. An ante-room should be provided for washing hands and
disinfecting legs before entering into the rearing area.
3. Doors and windows should be fitted with wire mesh to avoid
entry of uzi-fly into the rearing house.
4. Water facility should be provided in a rearing house for
cleaning/washing and disinfection and also for
humidification purpose.
5. The rearing house should have adequate lighting
arrangements for working during night.

15. 6. Electrical points in the rearing house should be provided for
using heaters, humidifiers, coolers and lighting the building
for workers during night hours.
7. Provisions must be made for exhaust fans for evacuating
humidity from rearing house during rainy days.
8. Arrangements should be made to ward off rats, lizards, etc.
and avoid entry into the rearing house.
9. Shade trees around the rearing house should be planted to
protect the walls and the roof from afternoon sun

16. REARING HOUSE
The size of the rearing house depends on the size of
mulberry garden, leaf yield and the number of eggs to be
reared each time.
While constructing the rearing house the following points are
to be considered.
 The land selected should be sunny, airy, dry and as far as
possible elevated and leveled.
 In temperate and subtropical regions the rearing house
should be constructed in north - south directions.
 In tropical regions, however the building should be in east-
west directions with doors facing north and windows facing
north – south.

17.  The building should be about 9-10 feet height and each
room should be more than 12-15 feet wide.
 The building should be rat proof.
 The building should have broad verandha at least 6-8
feet wide on all the sides.
 Sufficient number of windows should be provided to
admit free passage of air.
 The rearing house should have sufficient number of
rooms for storing leaves, chawki and late age silkworm
rearing and for mounting the spinning larvae.
 It should be possible to make it air tight for through
disinfection.

18.  The rearing room should be constructed in such a way
that it should allow the rearer to plan either for shoot
feeding or shelf rearing methodology.
 Raising evergreen trees like Cherry, Pongamia,
Jackfruit, Neem or Mulberry trees around rearing house
helps to maintain better rearing environment.
For late age silkworm rearing, under shoot feeding
methodology, the dimension of the rearing room should
be 30’ X 15’ and such two rooms are required to rear the
worms out of 400 disease free layings.
There must be provision for separate rooms for chawki
rearing and mounting of spinning worms

19. A rearing house planned for rearing capacity of about 300-
400 layings should have the following accommodation
under shelf rearing method.
1. Chawki rearing (one room) - 08' x 12'
2. Leaf storage (one room) - 15' x 12'
3. Late age rearing (One room) - 15' x 12'
4. Mounting of worms (One room) - 12' x 12'

20. Rearing stands: These are the
frames used for holding the rearing
trays and are placed in vertical
rows. It is made of iron or wood or
bamboo. The standard size is 2.5
m H. x 1.5 m L x 0.65 – 1.0 m W.
It has 10-12 cross bars with a
distance of 0.15m to accommodate
10-12 rearing trays. The size
mainly depends upon the size of
the trays.
SILKWORM REARING EQUIPMENTS
The following are the rearing appliances required for
silkworm rearing in shelf rearing methodology.

22. Rearing trays: These are
the portable receptacles
used for keeping the worms
during rearing and are
placed one above the other
in the rearing stand. They
vary in shape and size. They
are made up of either wood
or bamboo or plastic.

23. Rectangular wooden
trays: These are made of
lighter wood. The
commonly used trays
measure 3.5' x 2.5'. For
chawki (young age) rearing
the trays measuring 1.2x 0.9
x 0.12m are used.

24. Circular bamboo trays: These
are made of bamboo mat and the
diameter of the trays is generally
3.5’ to 4’. Bamboo trays are more
popular than wooden trays as
they are cheap, light and easy for
handling. These are mainly used
for rearing grown up worms as
they facilitate good aeration.

25. Ant wells: The standard ant wells are concrete or stone block
of 20 cm square and 5-8 cm height with a groove of 4cm
running all around the top as receptacle for water. They are
placed below the legs of the rearing stand and are filled with
water to prevent ants from crawling up the stand and harming
the silkworms.
Paraffin or wax coated paper: It is a
thick craft paper coated with paraffin wax
and has the melting point of 550C. It is
used to cover the rearing beds during
chawki rearing so as to prevent
evaporation of moisture and to maintain
high humidity in the bed.

26. Foam rubber strips: They are long
foam rubber strips of 2.5 cm width and
2.5cm thick. They are dipped in water
and kept all around the rearing beds in
the tray during incubation and chawki
rearing to maintain high relative
humidity in the bed.
Feather: Bird feather, preferably white
ones are used for brushing newly hatched
larvae from egg card to the rearing trays. It
can also be used for shaping silkworm bed
ad at the time of bed cleaning.

27. Chopping board: It is a rectangular
board of soft wood used for cutting
mulberry leaves. The dimension of
chopping board 3ft x 3ft with a
thickness of 5cms.
Chopping knives: Knives with
upward bent; 4-8 cm broad and 0.3 to
0.5 m long sharp blade with wooden
handle are used for chopping mulberry
leaves.

28. Mats: The mats are placed below
the chopping board prior to
chopping and used to collect the
cut leaves without soiling.
Feeding basins: They are used
for holding chopped leaves while
feeding to the worms.

29. Leaf preserving chamber: A chamber, the sides and bottom
of which are made of strips of wooden reapers and is used to
store harvested mulberry leaf. Wet gunny cloth is placed as a
lining on all sides and top and sprinkled with water
periodically to keep the leaves fresh.
Bed cleaning nets: They are made
of cotton or nylon thread and used
for cleaning the rearing beds. The net
mesh size of net is 2mm x 2mm for I
and II instar, 10mm x 10mm for III
instar and 20mm x 20mm for IV and
V instar worms, and for each tray
two nets are required.

30. Washbasin stand: It is used to hold
a basin containing 2% formalin
solution for disinfecting the hands
before handling the silkworms.
Foot cleaning tray: A pad made of
gunny cloth soaked in 2% formalin
solution and kept in a tray. It is placed
at the entrance of the rearing room for
disinfection of the feet of the persons
entering the rearing house.

31. Room heaters: They are used to increase
the temperature of the rearing room,
whenever it falls below normal.
Maximum and Minimum thermometer:
It is used to record the maximum and
minimum temperature of the rearing room.
Dry and wet Bulb thermometer: It is
useful in recording the room temperature
and humidity during the rearing period

32. Hygrometer: It is also used to
record the relative humidity of the
rearing room.
Chandrikes: They are also called as
mountages or cocoonages. These are
rectangular bamboo mat having
bamboo sticks at all the edges. The
bamboo tape is fixed on the mat at
one side in spiral form at a distance of
4-5 cm. The ripe worms spin the
cocoons between the two spirals.

33. Appliances used to support the spinning larvae
Mountages- These are contrivances used for supporting the larvae
when they spin the cocoons.
 Different types of mountages are used in different parts of India.
 In addition to support the spinning worms, the mountages should
satisfy the following requirements.
 Provide convenient space of suitable dimension for spinning
good sized cocoons.
 Should not promote formation of double cocoons, malformed
cocoons and flimsy cocoons.
 Should have provisions for drying up of the last excreta of the
worm prior to spinning and prevention of its falling on the
cocoons of other worms.

34. The common mountages used in India are:
a)Dried grass and twigs spread in shallow bamboo baskets
are used in Assam.
b)Dried weeds, paddy straw and fresh weeds are used in
Jammu and Kashmir.
In these two mounting and harvesting is difficult and require
more labour. Further, formation of double and deformed
cocoons is high.
 Should be suitable for easy mounting and harvesting.
 Should be cheap, durable, easy to handle, available easily,
occupy less space, allow free flow of air.

35. c) Chandrika which is formed by a bamboo spiral is the most
common mountage used in South India and West Bengal.
• This consist of a bamboo mat of size 1.8 m x 1.2 m supported
by split bamboo reapers on all sides.
• On this bamboo mat, a bamboo tape of 4 to 5 cm width is
wound in a spiral manner. The bamboo tape has V-shaped
poles supported by three long bamboo strips.
• About 1000 worms can be mounted on this mountage.

36. The defects of this mountage are:
i. percentage of flimsy and soiled cocoons are high.
ii. drying is uneven.
iii. harvesting and cleaning is difficult.
Other recently introduced modifications under trial
are screen type of bamboo mountage and plastic collapsible
mountage. These are convenient to handle and store.

37. d) Bottle brush mountage
It is introduced recently is not only cheap but can be
fabricated very quickly and occupies very little space
compared to Chandrika.
It consists of a thick coconut or jute fibre-rope into
which 6 to 9" sticks (midrib of coconut leaves) are inserted
very closely. The silkworms used the sticks as support and
spin the cocoons in the space between the sticks.

38. Rotary mountage:
This automatic free-mounting mountage saves labour and
reduces damage during handpicking.
It consists of a frame with 10-12 boards.
Each board is composed of 12 sections with 13 rows,
making a total of 156 chambers open at both the ends.
Ten such frames are assembled on a turning wooden
frame.

39. Rotary mountage
The mountages are kept above the rearing beds and revolve
at a low speed and ripe worms from the bed crawl and select
a chamber to spin the cocoon.
Double cocoon formation is less.
They are excellent cocoonages which encourage the
spinning of quality cocoons and save expenditure on labour.

41. Rocker sprayer: It is used for spraying
the disinfectants in the room and also to
spray the water to the leaf storage
chamber.
Chawki rearing stand: The stand of 1
feet height used to keep the chawki
rearing trays.
Humidifier: It is used to maintain the
relative humidity in the rearing room.
Leaf carrying basket: It is a bamboo
basket with narrow mouth and wide
bottom. Basket is covered with wet gunny
cloth and used to carry the mulberry leaves

42. Chop Sticks: These are two thin sticks of
bamboo (17.5 to 20.0 cm) and are tapering
at one end.
At the thicker end they are connected
by a small piece of thread and these sticks
are used like a forceps for picking diseased
worms and also the same can be used for
shaping the bed after bed cleaning.
Feeding stands: These are foldable stands
(3’ height) on which the rearing trays can be
rested at the time of feeding and bed cleaning
to increase the labour efficiency.

43. Shoot rearing stand: The stands are used to rear the late age
worms under shoot feeding methodology.

44. Thank you