Raising Silkworms By THL Serena Kimbalwyke MKA Sheri Israel 4620 Wilburn Drive South Euclid, OH (216)

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1 Raising Silkworms By THL Serena Kimbalwyke MKA Sheri Israel 4620 Wilburn Drive South Euclid, OH (216) In this class I will review period methods of raising silkworms. I will also explain how you can raise your own silkworms at home. Life Cycle of Silkworms The silkworm, Bombyx mori, is an insect that goes through four developmental stages in its lifetime. Egg over winters before hatching Larva the caterpillar or worm - stays at this stage for 25 to 40 days Pupa the cocoon stays at this stage for about 14 days Adult the moth lives up to a week to mate Mulberry Trees The leaf of the mulberry tree is the preferred food for silkworms, even though silkworms can and will eat leaves from other trees. Those who wish to raise silkworms must first secure enough mulberry trees or bushes to have an ample supply of leaves for the number of worms that are to be raised. There are specific instructions given in most period silkworm texts for proper planting, pruning, and caring for the trees. The mulberry trees should not have more than 25% of their leaves harvested or the trees may be damaged and not produce a sufficient quantity of leaves for the next year s crop of silkworms. Eggs Eggs can be obtained from the previous year s egg harvest, or can be purchased from egg brokers. The quality of the eggs is determined by their blue-gray color, by cracking them open with a thumbnail to check for moisture, or by submerging them in a liquid and skimming off the bad quality eggs, which float. Depending on the species of worm, the eggs must have over-wintered or kept in the cold for a period of at least three months, without freezing, before they will be viable and hatch. This can be accomplished by sealing the eggs in a container and burying them in the earth below the frost line for the winter, lowering them in a well, or keeping them in a building that will remain cool until the spring. Egg Hatching 1

2 There are several methods for hatching the eggs, all of which center on warming the eggs consistently and uniformly so that they all mature at the same rate and hatch as close together as possible. The eggs can be placed in a small pouch and carried close to the body so that the body heat warms the eggs, or the eggs can be placed in a small box and warmed by pillows, blankets, or cushions that have been heated by a fire. Alternatively, the eggs can be placed in a room that has been heated by a fire, however the fire should not be smoky or it could be injurious to the eggs. The eggs can also be allowed to warm naturally and slowly as the weather warms in the springtime, but this would cause uneven development of the eggs and the worms would hatch at different times, making future care of the worms more difficult. Worm Care When the eggs near the hatching stage, shredded young and tender mulberry leaves should be placed on the eggs so that the newly hatched worms will have food available. As the eggs hatch, the new worms should be removed from the hatching container into the rearing box. All the eggs that hatch in a six hour period should be kept together. This will make the care of the older worms easier since they will all be at the same stage of development. The worms should be moved by moving the leaves on which they are feeding, instead of attempting to move the worms themselves, so that the fragile worms are not damaged. The worms can be kept in boxes, on tables, in baskets, or in any variety of containers, which allow food to be placed on them and also allow air circulation. Since the worms will not leave the food source, the rearing containers need not be completely enclosed. While the worms are growing and maturing it is important not to disturb them too much, but they must be kept clean and dry. Their excrement, called frass, should either be cleaned away or the worms can be kept in a container with a bottom that allows the frass and dried leaf pieces to fall out of the bottom of the container. 2

3 The worms will molt five times in their lives to allow for growth and to get rid of the small outer skin. Each time they molt the worms will stop eating for a period of three to four days. The worms should not be disturbed while they are molting. They will resume eating in earnest as soon as the molting process is complete. As the worms molt and get larger they will require more food and must be fed more often to provide the freshest leaves to them. After the fourth molt the worms will eat voraciously for nine to fourteen days. During this time the silk glands fill up with fluid in preparation for spinning the cocoon. Shelving unit used to house the worms. From The Perfect vse of Silk-wormes by Olivier de Serres, 1607 Spinning When the worms are ready to spin their cocoons they will stop eating and begin to wander away from their food in search for a suitable place to spin their cocoon, mostly crawling upwards. They will become yellowish, more transparent, and turgid. At this time they can be transferred into a container which will provide them with places to spin their cocoons. These can be shelves with bundles of sticks next to them, drawers with arbors of twigs, or on any type of trellis which has spaces about one inch wide. This will make it easier for the worms to spin a cocoon without wasting a lot of silk on anchor threads to hold 3

4 the cocoon. The worms will spin for about three days, molt one more time inside the cocoon, and then change into a pupa. Five days after the cocoons are completed, they should be sorted by quality for breeding or selling. The best cocoons are white, firmly packed, complete, and thick. These should be saved for breeding purposes to secure eggs for the next year s crop. The rest should have the pupa inside the cocoon killed so that the emerging moth does not damage the cocoon. The pupa can be killed by steaming, boiling, or by putting them into a black bag or container and putting them out in the hot sun for three or four days. These cocoons can then be sold or used. Shelves with arbors to aide the silkworms in spinning their cocoons. From The Perfect vse of Silkwormes by Olivier de Serres,

5 Steaming the cocoons to kill the pupa inside. From Summary of the Principal Chinese Treatises upon the Culture of the Mulberry and the Rearing of Silkworms by Stanislas Julien (translator), 1838 Breeding The best cocoons are allowed to mature and become adult moths. These moths are flightless, having being domesticated by the Chinese thousands of years ago. The cocoons are strung up on a string, much like a popcorn garland, and are attached to a wall which has been covered with felt or other material. The moths emerge by secreting an enzyme, which loosens the threads of the cocoon so they are able to push their way out. They do not need to have food or water provided for them because their mouthparts are not functional. The male moths will then crawl a short distance to the nearest female and couple with her. They will stay coupled for up to 24 hours as the male transfers his sperm to the female. After the moths separate, the male moths will die. The female will begin to lay her eggs within 24 hours of separation. She will lay between 300 and 600 eggs. They are yellow at first, but will darken to a bluish-gray color in a few hours. They are now ready to be harvested and saved for the next year s crop of silkworms. The eggs should be stored in sealed containers, usually ceramic or glass, in an area that will be cold over the winter (but not freezing) such as in a hole in the ground, down in a well, or in a stream. Most species of silkworm eggs must spend at least three months in a very cold environment before they will hatch, although there are some species where the eggs can hatch a few weeks after being laid with no cold period necessary. 5

6 Adult moths breeding and laying eggs on cloth. From The Perfect vse of Silk-wormes by Olivier de Serres, 1607 Equipment Needed Mulberry trees Hatching container Small rearing box Should be lined with paper and have a solid bottom Large rearing container Can either have a solid bottom or woven bottom Spinning chamber Egg cartons in an enclosed container work well for this Emerging/mating container Should be completely enclosed to contain liquid waste and wing scales Egg laying container Small box lined with leaves or fabric Web pages Information on rearing silkworms and supplies 6

7 REFERENCES Anonymous An Essay on the Culture of Silk, and Raising White Mulberry Trees, the Leaves of Which are the Only Proper Food of the Silk-worm. By a citizen of Philadelphia Philadelphia : Joseph Crukshank 1790 Cipolla, Carlo M Before the Industrial Revolution : European Society and Economy, New York : Norton 1994 Corsucci, Giovanni (aka Giovan Andrea Corsuccio de Sascorbaro, Giovanni Andrea Corsucci) Il Vermicello dalla Seta (The Little Silkworm) Italy 1581 Fessenden, Thomas Green The New American Gardener : Containing Practical Directions on the Culture of Fruits and Vegetables : Including Landscape and Ornamental Gardening, Grape-vines, Silk, Strawberries, &c. &c. Boston : Carter, Hendee, & Babcock 1831 Geis, Frances & Joseph Cathedral, Forge, and Waterwheel : Technology and Invention in the Middle Ages New York : Harperperennial 1995 Hartlib, Samuel A rare and new discovery of a speedy way and easie means, found out by a young lady in England, she having made full proofe thereof in May, anno 1652, for the feeding of silkworms in the woods, on the mulberry-tree-leaves in Virginia London : Printed for Richard Wodenothe 1652 Johnson, Sylvia A. Silkworms Minneapolis : Lerner Publishing Group 1993 Julien, Stanislas, translator 7

8 Summary of the Principal Chinese Treatises upon the Culture of the Mulberry and the Rearing of Silkworms Washington: Peter Force 1838 Original version from China, dating back to 2205 BCE or earlier Kenrick, William The New American Orchardist; Or, An Account of the Most Valuable Varieties of Fruit, of All Climates, Adapted to Cultivation in the United States; With Their History, Modes of Culture, Management, Uses, &c. With an Appendix on Vegetables, Ornamental Trees, Shrubs, and Flowers, the Agricultural Resources of America, and on Silk, &c. Boston : Otis, Broaders, & Co Mokyr, Joel The Lever of Riches : Technological Creativity and Economic Progress New York : Oxford University Press 1990 Mola, Luca The Silk Industry of Renaissance Venice Baltimore : Johns Hopkins University Press 2000 Pullein, Samuel The Culture of Silk, or, An Essay on its Rational Practice and Improvement London : A. Millar 1758 Serres, Olivier de The Perfect vse of Silk-wormes Amsterdam, Theatrum Orbis Terrarum; 1607 New York, Da Capo Press, 1971 Stallenge, William Instructions for the increasing of mulberie trees : and the breeding of silke-worms, for the making of silke in this kingdome : whereunto is annexed His Maiesties letters to the lords liefetenants of the seuerall shieres of England, tending to that purpose London : Printed by E.A. for Eleazar Edgar, and are to be solde at his shop 1609 Straet, Jan van der A series of engravings entitled Vermis Sericus Netherlands

9 Vida, Marco Girolamo De Bombycis mori (On the Silk Moth) Italy, 1527 Translated into English verse by Samuel Pullein The Silkworm: A Poem in Two Books. Dublin : S. Powell,