Serving the Tiny Masters:

Serving the Tiny Masters:
- adventures in home sericulture -

I open the door, and I can hear them. The sound is only a soft, quiet pattering, like rain on the roof ... but I know what they're thinking. "Feed us. You must feed us. Bring the food here to us, now." They wave back and forth hypnotically, like tiny cobras - I have to obey.

One month each spring for three years now, the Tiny Masters have ruled my life. I wake early and stumble bleary-eyed out into the yard to fetch their food. I change their trays every other day, adjust the temperature and humidity in their room so that they will be content, fuss over them and attend to their needs. The main need is food. Every day, three times a day. For the fourth and final week, four times a day. They are always hungry, the Tiny Masters.

I got started raising silkworms in 2001. A friend of mine said that she had raised them in school as a child, and they were an easy and fun project. I have been weaving for over a decade now, as well as using silk in my soap, and the vision of home-made silk for special projects was very seductive. I started looking into the requirements, and found them to be very simple, although quite firm - a clean, toxin-free environment, a ready supply of fresh mulberry leaves, warm room temperature (78' to 88'F for fastest growth) and time. A lot of time.

Silkworms are caterpillars. They are the larval stage of the white silkmoth, Bombyx mori. They are the world's only truly domesticated insect, having been bred and selected for thousands of years, mainly for quality of silk (color, strength, volume) but also for ease of rearing. The end product is a very efficient leaves-into-silk machine; after four weeks of voracious eating, each worm will spin a cocoon that looks like a Styrofoam "peanut" composed of up to a mile of unbroken silk fiber. The worms in their current state could never survive in the wild, since they have no chemical or physical defenses to protect them from predators. The larvae (the worms) are white and soft-bodied (no camouflage or spines) and the imagos (adults) are fat-bodied and totally flightless. There is another semi-domesticated type of silkworm that produces "Tussah" silk; these feed on oak leaves, and have a very different lifestyle than the classic bombyx silkworm. They're somewhat less receptive to hand-rearing at home, but eggs are occasionally available if you're feeling really adventurous..

I order silkworm eggs in the spring. I get mine from Mulberry Farms mainly because they're less expensive. I have tried to over-winter the eggs in cold storage, but have not yet hit upon the correct balance of temperature, humidity, and timing. Hopefully, I've gotten this sorted out, and starting this year I'll be able to rear from eggs I stored from last year's moths. The eggs are the size of a ball-point pen's ball, and if you order them, come attached to the bottom of a petrii dish or a piece of paper. If you have eggs from your own moths, they're likely to be on whatever substrate you have for them to lay on (I use freezer paper) and laid out in a round-ish pattern that the moth seems to prefer.

The eggs hatch usually within a week of arrival. They need about two weeks from the time they're removed from cold storage, to the time they hatch, but most of the mail order houses send them about halfway through that time. Upon hatching, the larva are tiny - about the size of a typewriter dash. They are called "kego" by the Japanese, which means "hairy baby". The Indians call them "chawki" silkworms. They are also called "Ant Silkworms," because they really do look like small brown ants. They typically all hatch on the same day, and usually at dawn, even if they don't see the sun. Don't ask me how they know, but they seem to. There are always a few early risers the day before, and a few per day for a couple of days after.

The tiny kegos have to eat within four hours of hatching, or they die of dehydration. For the first couple of days, they require only the tenderest tip leaves of the branch. Some folks say that you need to chop the leaves up; I find that tearing them in half is sufficient, because they seem to just start chewing wherever they feel like. These leaves need replacing about three times a day, mainly because they are tender and dry out easily. The worms receive all their fluids from the leaves they eat. The leaves must be fresh and clean and unwilted, but not damp. If the leaves are wet, the worms drown. I usually keep the worms in a tray with a lid to slow the drying of the leaves, but if you take this route, be vigilant about mold. If the leaves mold, and the worms eat the mold, they die. The worms expect to be fed; that's why I call them the Tiny Masters. When you open the lid of their container, they wave their heads around, reaching for the leaves they know will be immediately forthcoming. The leaves have to be placed right on top of the worms; if you place a worm six inches from a juicy leaf, it will die. They won't let go of a leaf except to crawl to another leaf, which is a great advantage in hand-rearing - they don't crawl out of a tray or dish.

Silkworms grow very fast. They will increase their body size by 10,000 times within their one-month larval life. Within four days, they will shed their skins, and graduate to the second instar. Instars are the stages of larval development; there are 5 of them between hatch and cocoon, each one accompanied by a new skin and a growth spurt. The process of shifting skins is called ecdysis; this is a characteristic of all insects, as their exoskeletons are only slightly flexible, and don't allow for much growth. The second instar larvae are gray and smooth, where the first instar was dark brown and hairy. Each instar has a significantly larger head, and you can easily tell the new second-instar worms from the first-instar worms by the size of their faces. Later stages are closer and closer to pure white. After the first two instars, which each last for four to five days, each successive instar lasts about a week. Each time the larvae are getting ready to shed their skins, they will spend several hours not eating, sitting immobile with their heads upward. Afterwards, you find the shrugged-off skins on the bottom of the tray or attached to a leaf, looking like where a lazy husband stepped out of his pants.

The bigger they get, the more they eat. In the fifth instar, the larvae will begin to change their metabolism; they go from primarily increasing their own body mass, to primarily forming silk proteins. Their thorax area gets larger and larger, and they eat nonstop, night and day. After this week of gorging themselves, the worms will begin to wave their heads about as if praying ecstatically. This means that they are feeling the need to cocoon. They start to sketch silk onto anything around them, and climb upward. It is the only time in their life cycle that the worms will crawl out of their tray if allowed.

The best cocooning arrangements allow the worms to have individual compartments. This maximizes silk output by allowing each worm to make a perfect cocoon. Egg cartons work, as do small sections of paper towel tubing. I have also, when faced with the sudden cocooning of about a thousand worms at once, made little artificial bushes using wire and the branches from the mulberry tree. They climb up it, find a likely spot, and start making little silk hammocks. This silk is called "flossing." It is tough and not always one continuous strand. After they have their hammocks well built, the worms begin the serious cocooning. The perfect cocoon is a long oval with a "waist" in the middle, and has a wrinkled surface. Some strains of silkworm will spin pure white, others spin a golden yellow. There are some rare strains that spin cocoons of other shades, but these are not readily available. The silk fiber is actually made of two smaller strands called "baves." Silk consists of two proteins - fibroin and sericin. The fibroin makes the long strand of the silk, and the sericin binds the strands together in the cocoon. Cocoons which have been "degummed" have been simmered in a bath of chemicals (see "making mawatas") to remove the sericin. Most silk is processed with the gum on it, since it protects the delicate fiber, and then the sericin is removed after spinning or weaving. Silk used for soapmaking is typically already degummed.

In commercial silk production, most cocoons are stifled. This means that they are treated with heat or steam to kill the pupa inside. If the moth hatches out, then the cocoon cannot be reeled off; reeling produces the finest silk. Cocoons which have hatched out (ecloded) are still useful for spinning silk, and can be made into hankies or caps. These are ways of stretching out the fibers to make spinning from them easier. If the cocoon is not stifled, then in about two weeks the moth will secrete a brown goo, which softens the sericin gum, and push its way out of the cocoon. The adults, also called imagos, are squat-bodied, covered in soft fuzz, and totally unable to fly. The males can detect the scent of the females from hundreds of feet away, using special receptors in their comb-like antennae. They mate for a few hours, and then the female will lay between 200 and 500 tiny eggs. The adults are not equipped with working mouth parts, and since they cannot eat, they die soon after mating. Their entire life cycle, from eggs to eggs, takes about six to eight weeks.

These worms are in their third instar. They're still relatively small	This is a bunch of fifth-instar worms, about 3.5 weeks old. I've just cleaned their tray, and given them a fresh leaf.	Within minutes, they'll reduce it to mere veins.
Kind of like...	vegetarian piranha.

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Bombyx mori - the silkworms' blog!

This is a photo-intensive, blow-by-blow description of my silkworm rearing. If you want to read more information about the process, check out Serving the Tiny Masters.

When the mulberry tree looks like this, it's time to take the worm eggs out of the fridge! These catkins are quickly followed by the tender new leaves, the kind that the hatchling silkworms love to eat.

The Bombyx mori eggs were taken out of cold storage on March 17. I keep them in a special warm room that I use for drying my soaps; any place that will stay at or above 72' or so will work, but they'll grow faster and be healthier between 78' and 85' F. Healthy eggs are plump and not dessicated. If you look carefully, you can see the caterpillar curled inside some of the eggs. The baby cats are curled head-to-tail like a letter C. Bombyx mori undergo diapause in the egg - similar to hibernation - they pass through the winter in a barely-alive state, and perk up when it gets warm again. Because they're so thoroughly domesticated, these two states are "in the refrigerator" and "out of the refrigerator."

Here, you can see the sophisticated and classy egg-hatching setup. Yes, it's a salad container from a fast food place. There are probably eight or nine hundred eggs here; I just made a guess, selecting some from each of several different batches to ensure genetic diversity. As they grow and need more space, they'll be transferred to big deli trays with lids. I keep a moistened piece of tissue in here, to keep the eggs from dehydrating. Whether you need this or not will depend on your climate. It's essential that the eggs don't get damp, or mold - if there is condensation on the inside of the lid, it's too moist or the heat source is too direct. March 17, 2004.

It typically takes 10 - 14 days for the eggs to start hatching. It depends on several factors, including temperature, humidity, and the level of development before the eggs went into the fridge. Apparently some of these were ahead of schedule, because they started hatching out in just 7 days. March 24, 2004.

These little guys have to start eating almost immediately, or they dry out and die. You can see the tiny holes they've chewed in the leaves. The hatchling silkworms are called "kego" in Japan, or "chawki silkworm" in India. "Kego" is translated on one Japanese website as "hairy baby" - they are covered with little black hairs.

Here, you can see the size of the hatchlings.

The first few usually hatch a day before, and then the mass hatching starts on the second or third day. This makes Bombyx mori easy to rear, because they will go through all their various stages and change simultaneously. Note that the unhatched eggs have a "blue" cast to them - this is because they will hatch soon. Overall hatch rate on this batch was well over 90%. The brown staining on the paper was from the moth. The mass hatching makes them look like a hill of ants; a Chinese name for this stage is "ant silkworm." March 25, 2004.

This is the best way to move the kegos around. This is a synthetic sable #1 brush; anything from a #0 to a #2 will work fine. I find that they need to be "wiped" off the end to put them down on a new leaf. Each worm makes a silk "safety line" and attaches itself to the leaf it's on; that makes them easy to sweep up and move.

This is the third day. The worms have more than doubled in size already. Just above the center of the photo, you can see a tiny new-hatched worm; compare its size to the ones around it, and you can see how much they've grown! Also, you'll notice that instead of just nibbling holes in the leaves, they turn the leaves into lace. The leaves are held together by the veins alone.

Overall, though, they're still quite small. March 26, 2004.

A couple of days later, the kegos are changing their skins! The second-instar worm at the top has already shifted his skin; note the larger face plate and the gray coloring. The worm below is about to change - you can tell because his white shiny skin looks too tight for his body. His tiny face will be replaced by a much larger one, which will allow for faster eating and more growth!

These are second-instar worms with the dime for scale.

This worm has crawled off the leaves to change his skin. I call this "praying" because he looks like he's in prayer or meditating - they sit with their heads lifted up, immobile, their legs folded before them, for hours or even a whole day.

When the worm steps out of its skin, it leaves it behind like this. Imagine someone slipping out of their pants and just leaving them in a puddle on the floor. If it's my partner Chris, they have the socks still in them. March 28, 2004

The worms are big enough now that I change them up to a larger tray. This is the kind of tray that they will live in for the rest of their life cycle; as they grow, I just split them out to additional trays. This is a deli tray - if you're not fortunate enough to work for a company that buys them to throw parties or treat the staff to cheese and fruit (have I mentioned that I love my job??) see if you can talk your local grocery store deli counter out of two or three. Otherwise, you can buy them at places like Sam's or a restaurant supply house. The lid isn't really necessary, because the worms won't crawl far from the leaves until it's time for them to spin - but it helps keep the leaves from drying out.

To make the cleanup easier, I line the trays with a piece of freezer paper folded and cut into a circle.

When I transfer the worms, I do it by picking up the leaves they're eating and moving leaves, worms, and all to the new tray. This allows me to leave behind the older leaves beneath. I find that I can build up 3 to 5 layers of leaves before they start to get moldy and nasty beneath; it varies depending on temperature and humidity. Individual worms that are left behind on the litter can be picked up *very gently* with tweezers or forceps, or with a paintbrush. It's easy to crush them if you use your fingers.

This is the amount of leaves they're eating right now. It's about 4 pieces of branch, each a foot or so long and only as thick as a pencil. The basic idea is to have enough leaves to entirely cover the worms; imagine covering a pizza entirely with pepperoni slices. If you put leaves a few inches away from a worm, it's a dead worm.

This is what they look like once they've been fed. After this, they're good for another 6 to 8 hours. The more you feed them, the faster they grow. I usually feed them first thing in the morning, at lunch, after work, and before bed. They don't need feeding during the night, although I'm sure they'd appreciate it. March 28, 2004.

The worms have now begun to change into the third instar. This one is waiting for the skin to split... he will walk out of his skin after shrugging off his old face for the new one. March 31, 2004.

Here, you can see a worm that has just shed its second skin. Note that the head is large and gray; it will darken over the next few hours. You can see the shed skin behind it - the worms attach their claspers to the surface, and just wiggle forward out of the skin to shed it.

Here, you can see the shed skin more clearly.

In this shot, you can see the second-instar face hanging from the jaws of the third-instar face. The faces pop off like masks.

For scale. The worms are getting bigger by the day.

And today, I split them into two trays. The ideal is to have 1/3 of the surface space of the leaves occupied by worms; when they get large enough that they don't have room to turn around comfortably, it's time for a bigger tray. Fortunately, these deli trays stack on top of one another, so the extra space just means more height. Feeding time is a bit of a juggling act, and the trays end up spread out across the cabinet, but they store quite neatly between feedings. March 31.

Today, the worms have started changing into the fourth instar. This change, like the ones before, means a bigger skin, a bigger face, and more food. April 2. There are several things to see in this photo. The worm in the center is about to change; it is going through the period of rest before slipping its skin. On the lower left side of the photo you can see a slipped skin - they are larger now, and very noticeable. On the right you can see a new fourth-instar worm, with the much larger head. And center top, there is a worm that failed to make the change. If they are disturbed during the changing process, whether by human hands, or by other worms knocking them over, it can cause them to get stuck and die. This worm is still wiggly, but will most likely be dead within a day. If you have worms that get sick, turn dark, become limp, or ooze any fluid from either end, they *must* be removed immediately from the other worms. If you feel like the little guy would recover if you only gave him a chance, you can put him into a tiny "hospital" tray with his own leaf. Sometimes they do go ahead and recover. Most times, they die. There are bacterial and viral diseases of silkworms that can wipe out an entire crop very quickly. Hygeine is the most effective thing that to prevent disease from spreading. Make sure to wash your hands after touching any sickly worm, and after cleaning up the trays. April 2, 2004.

At this point, the worms are large enough to handle gently by hand, instead of lifting the whole leaves. I usually count the worms when they enter the fourth instar; when I change their trays, I put ten at a time onto leaves, and transfer them to new trays. The size of trays that I use, 200 fourth-instar worms fit comfortably onto one tray, so that's 20 leaves with 10 worms each. This year, I have about 750 worms.

Here, you can see the 200 worms on the tray. This is good spacing - they are not crowded, and have plenty of room to move around. Each worm should have three times as much floor space as it needs sitting still. April 2, 2004.

The fourth instar worms keep growing. Here are some of the worms off the leaves for cleaning-time. I skipped the stage of putting 10 on a leaf, because it's faster this way. The dime shows that they're continuing to get bigger by the day; the largest ones are about 1 3/4 inches long. You may notice that some of the worms, particularly one just to the left of the dime, and one in the upper left corner, are standing up on their hindlegs; unfortunately, because this is a still picture, you can't see that they're doing the Food Dance! They wave their entire upper bodies around in a wide circle, almost brushing the paper in front. They do this until food falls on them. If they don't touch any food after a few circles, they move forward a couple of steps and try again. This is because they are so thoroughly domesticated; the wilder types of caterpillar don't mind walking a little ways for food, and don't always expect it to be served up. April 5, 2004

And here's one of the four trays. The trays stack upward, so they don't take up much counter space, except at feeding time. Another thing that becomes really noticeable at this stage is the sound of the silkworms. They make a noise similar to rain on the roof, or a huge bowl of Rice Crispies. Some sources will say that it's the sound of them eating, but it's actually mostly the sound of their claspers as they move - they make the sound even without leaves. Five or six worms in a dish will be distinctly audible, but when you open up 4 trays to feed them, it's as loud in the room as if it were actually raining outside. It's a very peaceful, soothing white noise. It's even louder as they get bigger. April 5, 2004.

Today, the worms started changing to the fifth instar. You can see this one in the center stepping out of his skin. The change starts with a shrugging motion repeated several times, and then the worm starts to wiggle forward out of the old skin. The new head is much larger than the fourth instar's; I call this the Turbo High Speed Eating Head. Silkworms eat almost 90% of their total intake during the fifth instar, so that means that they will eat nine times as much in the next week as they have eaten, total, over the past three weeks. It becomes a busy chore keeping them fed.

Right now, they're eating this much mulberry three or four times a day. This is three branches with a diameter at the base of about an inch. This will triple or more over the next few days. As soon as the worms are done with the change, they will be transferred from 4 trays to 8.

April 9. These two worms are doing totally different things. The one in back is in the "Prayer Position" waiting for its skin to split; the worm in the front is waving its head around looking for food. It is important not to disturb worms when they are in the Prayer Position, because it can interfere with their changing of skins. When the worm is getting ready to change, it spins a little pad of silk and attaches its claspers onto it; then when it is ready, it wriggles and walks forward, leaving the skin attached to the silk pad. If you pick up a worm in this stage, you will hear a ripping sound as the silk is pulled free - sometimes the silk comes up with the worm, sometimes the worm loses its grip on the silk. Either way, it can make it difficult for the worm to shed its skin. If the majority of the worms are in the Prayer Position waiting to change, you can skip a feeding or two to help them out - if there is a mix of hungry worms and resting worms, just feed lightly so that the resting ones don't get covered with leaves.

This is what happens when a worm gets stuck in its skin. This happens even with the most carful handling; other worms walk across the worms that are trying to change, and knock them off their pads. Most often, I find that I have accidentally moved a worm that wasn't ready to move. Since the worm breathes through its spiracles (the black dots along its sides), it needs to shed its skin fairly quickly to avoid suffocation. This worm is in my "hospital tray" - notice that the worms behind it are a kind of rusty brown color. They will typically continue to darken, and eventually die, but sometimes they recover and can rejoin the others. Sometimes you can gently "peel" a worm that has gotten stuck in its skin; you have to be very careful to avoid ripping its delicate new skin. The old skin peels all the way off like a sock.

This is a full-grown fifth-instar larva. In this stretched-out position, it is two and a half inches long. It will eat voraciously, making lots of protein to spin its cocoon from and storing up fat for its pupation and its life as a moth.

This year, for some unknown reason, I ended up with some white-faced worms. They don't have the usual black brow markings that the regular kind have. I know that there are different races of silkworms, and this may be a throwback to some previous breeding in the line.

This worm has the usual pattern of markings. The bulge behind its head will get bigger and bigger over the next week or so as it fills with silk protein.

	This isn't how I usually feed the worms, but I love this demonstration of their eating speed. These photos were taken at five minute intervals.
	The worms attack the leaf from all sides...
	Within minutes, they will have reduced the huge leaf to mere veins.
	Kind of like...
	Vegetarian piranha.
	Total time elapsed: 30 minutes April 9, 2004

This is the current setup of trays. I like them because they stack up - it's still a significant amount of space required at feeding time, but at least they put away into a neat pile. April 11, 2004.

The worms have begun to spin. The worms stop eating and go into a rest, like when they are going to shed, but instead they dump out the undigested food in their gut, and start to wander and spin silk thread everywhere they go. The worm in the front has changed over and started to spin; the worm behind it hasn't yet. Note how much smaller the worm in front is - they lose a lot of size when they make the change. They also develop a translucent yellowish shade that the camera can't quite pick up - they look a little waxy, and the greenish hue (caused by the mulberry leaves inside!) that they usually have, disappears.

The gut dump is something I wasn't prepared for the first time; none of the sources I read mentioned it. Some times it's just a loose green version of their regular frass; other times it's a wet nasty splat. If caterpillars do this any other time except when they're getting ready to cocoon, they're sick and should be isolated from the brood. After dumping its gut, the silk worm will never eat again; it lives off of stored fat through its entire spinning, pupation, and adult life.

The worms will wander around, and find a space to spin. Ideally, they want a close environment; they will spin up in the leaves, if you let them. Their second choice is in the lid of the top of the tray. Either of these locations tends to lead to slightly irregular cocoons; it's best to put them into a dedicated space to spin. I use toilet paper tubes, although when I had a thousand worms cocooning at once in 2002, I made bushes from the discarded mulberry branches. This is the only time that the worms will entirely leave their trays if they're not covered - if you raise them in a box or aquarium, you could find worms up in the corners of the room or in your drapes. This worm has begun spinning the "flossing" of his cocoon - this forms the framework that will support the cocoon, sort of like a hammock. This silk is slightly thicker than the reelable filament, and is not continuous. It is used in making spun silk thread, and is called cocoon strippings, blaze, or keba. The worm will spin non-stop for up to three days before shifting its final skin and becoming a pupa. The worm waves back and forth to spin the flossing, but once it gets the framework set up, it will make a slow, deliberate figure-8 motion with its head, thousands and thousands of times.

After a couple of hours, the cocoon is dense enough that you can no longer easily see the worm at work.

But if you hold the cocoon up to a strong light, you can see through the cocoon - at least for several hours, before it becomes totally opaque. April 11, 2004.

April 15. The worms have begun spinning in earnest. It's like an avalanche - the first few days, it's two or three each day - then, all of a sudden, dozens and dozens each time I check. When the worms crawl upward onto the tray lid, or start to spin up in a leaf, I transfer them to the tray full of tubes. The tubes are stacked end-upward like a honeycomb, providing a perfect little space for each worm. You can cover it with the bottom of the tray, if they are adventurous. Once the worms have a good start, each tray can accommodate a second worm, inserted at the bottom - don't put it above the worm in progress, or it may stain the cocoon with its droppings.

This is the full tray. There will eventually be about 4 of these; each one will hold about a hundred tubes, which can be doubled up to hold 200 worms. Once the cocoons are firm and opaque, you can pull them out to make space for more. The worms generally won't crawl out of a tray like this (the plastic edges are forbidding, and they never want to crawl down... ) but I wouldn't lean them against a wall or drapery. April 15, 2004.

NOTE: The following section describes the processing of the cocoons to kill the larvae inside. If this troubles you, please don't read it.

This is the crop of cocoons. The very largest and finest cocoons are saved for breeding, but the remainder are stifled (killed) to prevent the moth from hatching and destroying the silk. Cocoons should be stifled after the worms have changed to pupae (about 3 days after spinning) but before the moths would begin to hatch (about 2 weeks after spinning). Hatched cocoons can be used for spun silk, but are no longer useful for reeling from. Reeling produces the most regular, lustrous, and desirable silk. April 21, 2004.

First, the blaze is separated from the cocoons. This is the first thread that the worm spins when beginning the cocoon. It is called cocoon strippings, blaze, or keba. It is useful in making spun silk. Any cocoons that are soft, stained, or irregular are sorted out. Some will be discarded, others will be added to the silk used for spinning.

The way that I prefer to stifle the cocoons is to bake them in a 180'F oven for 30 - 40 minutes. If your oven won't go below 200'F, be careful that the cocoons don't scorch. It is also possible to freeze the cocoons to stifle them, or to place them in hot sunshine. The reason that I prefer the oven, is that it dries out the pupae so that they will not rot and smell bad. They do tend to smell, but the smell of the under-baked ones is really rank. If you choose freezing, make sure to keep them frozen until it's time to reel them. For information on how to reel the silk, click here. April 21, 2004.

May 4, 2004. The first signs that a cocoon is about to hatch, is that it will become wet on one end, and often rock back and forth. The wet spot is from an enzyme the moth squirts out of its head to loosen the coon threads. Cocoons usually hatch at dawn, and usually about two weeks after the start of spinning.

After much struggle, the moth will begin to push its way out through the damp spot on the cocoon. The moth will emerge damp and bedraggled looking.

The moth wiggles its way slowly out. The process is complex; first, it pushes forward with its head, then, it swells up the sections of its body one at a time, slowly moving forward.

Eventually, the moth pulls free of the cocoon. They will often grab on to an adjacent cocoon, or climb up the side of their own; I provided my finger to give the moth something to grab onto. This moth is a female; you can see her abdomen is distended with yellow eggs, which you can actually see through her skin in between the furred stripes.

The female will rest on the cocoon, and spread out her wings.

This moth is a male. You can tell by the much smaller body. Other than the female's huge egg-laden abdomen, the two sexes are very similar.

Not long after she emerges, the female will begin to scent. She sticks out a special gland from her abdomen which exudes a pheremone. Many of the Saturniid moths wait until dark, or even the following day, to scent; Bombyx moths scent usually within seconds of emergence. The males are unable to fly, but the pheremone drives them crazy, and they buzz their useless wings and walk excitedly around. It's actually kind of comical.

The male moths are driven wild by the pheremones. They will try to mate with anything even vaguely moth-sized, including cocoons and each another. The brown stains behind the moth are from the fluid that the moths squirt out from their bodies - they're especially likely to squirt when excited or startled. It's called meconium. The moths use the fluid to inflate their limp wings after they emerge; once the wings have hardened, they withdraw the fluid and secrete it as waste.

Once they finally find the female, the male grasps the female by the abdomen, and they settle down. The males flap their wings in short bursts for a while, and then stop altogether. They will remain paired like this for twelve to twenty-four hours.

In order to control the pairings, I place pairs of moths under plastic cups. This also helps keep the pattern of egg laying neat and clean.

After mating for 12 to 24 hours, the pair will separate, and the female will begin to lay her eggs. Most females will lay between 150 and 300 eggs over the course of two to three days. Some moths can lay as many as a thousand. The eggs start out lemon yellow, and over a day or two will fade through tan to dark gray or black. If they do not change colors, the eggs are likely infertile. After they change to dark gray, they can be placed into cold storage. The most convenient way is to trim the paper into colony-sized circles, and place them inside a jar or freezer bag, and put them in the door or a crisper drawer. The main body of the refrigerator can get too cold for them; ideal temperature is between 35'F and 40'F. If the eggs are not refrigerated, sometimes they will hatch, and other times they will just dry up and die. May 7, 2004.

That's the whole life cycle of Bombyx mori. It starts over again with the eggs in the spring!

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Reeling Silk

This is a little photo-journal of the silk reeling process as I do it. I've raised silkworms for three years now, and this is how you go about getting the cocoons turned into thread.

This is most of the basic setup. There are two crockpots, one for pre-heating and one for the cocoons that are being reeled; there are forks and slotted spoons, there is a reel (from the 1850's, we're guessing) and a ball winder, and lots of cocoons. The work surface is covered first with plastic bags, because the cocoons drip, and then with towels. Silk will get *everywhere*, and if you don't have something like a towel handy to wipe your fingers on, it's almost impossible to get free of it.

I begin by simmering the cocoons in the hot water. They need to get pretty drenched, but they don't need to boil at all. We call this "Pupa Soup." It smells like dead bugs, because, well, dead bugs. Once the cocoons have loosened up a little, and maybe you've held them under the water with the spoon until they stop fizzing, then you can start the Quest for the One True Thread. Each cocoon is made from one thread. The trick is finding it. You start with the toothbrush, which is like taking apart a ball of yarn with a serving fork. You separate out a lot of dead ends, and then you hopefully find the Right One.

In the process of finding the right end, you waste a lot of silk. It's OK, because it isn't stuff you can reel anyway; it's short bits from where the cocoon was just getting started. Keep this, though - you can degum it and use it to spin with. This is where silk noil comes from. You can see the waste from two cocoons; some produce more than others. I take it off by wrapping it in a figure-eight shape around my index and ring fingers, while holding the cocoon in the other hand.

When you are about to the One True Thread, it will look much like this. I still have one or two extras here - but once you get the One True Thread, the cocoon tends to unravel, and won't pose for the picture.

Chris is intrigued with the Pupa Soup, and decides to give it a try.

The Pupa Soup is not delicious.

Here, if you look *really* close, you can see the individual threads coming off all the cocoons. I'm holding them up.

You can check to see which cocoons are connected to the reel, by pulling the bundle of threads to one side... I call this "herding" the cocoons. The ones that are detached will just float, the ones that are attached will follow the threads.

These are the cocoons, just about to start reeling. I ended up switching pots later on, though, so don't be confused if you notice it changing. The threads showed up nicer against the dark green, so I used this one for the pictures. Notice the stand, and the little bone button hanging over the pot - this will help to condense the multiple cocoon threads into a single filament - reeled silk!

Closeup of the button. You can see where it's tied onto the Bunsen-burner stand with a twist-tie, and the other hole has the threads going through it.Then, I attach the thread to the reel, and begin reeling the cocoons.

The blur in the middle is the reel turning quickly.

Here you can see the reel with some of the silk on it.

If your cocoons do this a lot, they probably haven't soaked in the hot water quite long enough. Hold them under with a fork until they get a little water-logged, and that should do the trick. They won't sink, but they'll half-float, and the water makes them a little heavier. It also helps them unwind.

As the reeling progresses, the cocoons become thinner and thinner. You can see the bug inside many of them. When you've reeled all the usable silk from the cocoon, they will either drop off in the water, or fly up the thread, sometimes with a surprising wet splat.

This is one that went up the thread. The unusable silk at the center of the cocoon is called the "cradle" - when the cocoon runs out of good thread and the cradle is all that's left, I call that "cradled out."

When the silk is all reeled on, it's time to re-reel. Sometimes this goes directly to the ball winder, but I decided to try putting it onto another clock reel first. It seems to help reduce breakage, because of the angles and the winding mechanism.Here is the silk being wound onto a toilet paper tube. After enough tubes are made up, they will be reeled together into one thicker thread, then dyed and used for stitchery or weaving. If desired, they can also be twisted using a spinning wheel, a process called "throwing."

And voila', there's the silk.

This is the pile of noils; it's silk waste and cocoon cradles. You can use this in spinning, or add it to your handmade soap (in the lye water).

This is what's left of the cocoons.

I take the pupae out, and toss them away.They're an important source of protein for many countries, though. As Chris pointed out earlier, they are not delicious. I have eaten one, just to check. Really. Tastes like bug. If you don't raise them yourself, don't eat them - they will be even less tasty if they're not fresh.If you want to learn more about the rearing and handling of the silkworms themselves, check out my earlier entry, Serving the Tiny Masters.

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Silk Reeling - Improved

It's been over a year since I posted the original set of reeling pictures, and I've learned a lot. This is how I reel silk these days. It's based on information I've gotten from a variety of sources, mostly old books. There is virtually no good modern literature explaining how to process silk by hand - a condition I'm trying to remedy.

I start out by soaking the cocoons for a few minutes. This helps make it easier to soften the gum on the cocoons. I start by filling the jar with the cocoons, then with very hot tap water. After five or so minutes, I pour out the water and replace it with very cold tap water. If you try this at home, make very sure to use a tempered Mason jar; thinner jars can't handle the temperature shock. I use a narrow-mouth jar because it helps keep the cocoons down.

After the cocoons are soaked, I pour them into a kettle of water just removed from the boil. You can't see it in the pictures, but there's a little single burner under the kettle. I have put a sieve on top of the cocoons to keep them under the hot water; it's helpful but not necessary. The cocoons will fizz and sizzle vigorously; the air inside is being expelled as they heat up, and the gum is softening.

After the cocoons have stopped sizzling, it's time to start groping them for ends. I do this with a dish brush. The traditional version looks like a tiny whisk broom, or a wok broom; they are usually made of rice stems or twigs. You can see that the cocoons are floating low in the water now - they've drawn in some water, so that they're about a third full. It makes them much easier to reel. I poke at the cocoons with the end of the brush, and also make a stirring motion around the surface of the water with it, which picks up the filaments from the cocoons.

This is what you catch with the brush. You get several cocoons with each swipe, and start pulling the ends from them. As you pull off all the ends together, you will find that they start separating out - some cocoons will drop off, others are clearly connected to the strands in your hand. The strands pulled off during the process will wrap around your hands, cling to your clothes, and get on your nerves. Snap the bundle of strands often, and wipe it off your hands and brush. The silk waste produced by this process is called "knupps", and is used for making silk to spin.

Here, you can see the threads attached to the cocoons. You can find which ones are attached, by dragging them from one side of the kettle to the other, and by watching to see which ones bob around. If you want to see the threads, look in the dark areas right above the bunch of cocoons, against the side of the kettle. Each cocoon's filament is about 2 to 3 denier; a denier is one gram per nine kilometers, or about four and a half million yards per pound. Needless to say, they're very thin.

I use a slotted spoon to raise the connected cocoons and transfer them to another bowl, with the ends draped over one side so you can find them. Repeat this step until all the cocoons are in the second bowl. I drape a piece of damp paper towel over the side of the bowl, so that I can stick the filaments to it. They're very fine, and easy to lose track of. Fill the bowl from the front to the back, so that when you pick up a cocoon from the back, its filament won't be under the ones in front of it.

Now, it's time to set up for the reeling. I arrange about fifteen cocoons together to make the reeling strand. Here, I'm showing the method for picking up the cocoons. This assumes that you're winding the reel right-handed; if you're using the opposite side, then reverse these. Traditional Japanese reels use the left hand to crank the reel and the right hand to feed the cocoons; I like to crank with my right hand because that arm gets fatigued less easily. There's a certain amount of "Emperor's New Clothes" involved in this - you honestly can't see the filament a lot of the time. I'll hold up my hands like I've got thread in them, and you pretend you can see it, OK? A lot of this process is done by feel. Seriously, though, you can barely see the filament coming off the cocoon; it goes diagonally down and to the left from the middle of my thumbnail.

The following few pictures will show how to drop the cocoon while holding on to the thread. It's something I've worked out based on text and illustrations in a couple of old books; use whatever works for you.

Here, I've wrapped my fingers around the thread. Yes, I know it's invisible. Trust me, it's there. You can see just a little bit, below the pinky finger. The best way I can explain, is that you just make the motion, knowing where the thread goes - you'll realize when you drop it, if you've got one that doesn't have the end attached. You can go through the motion with a spool of thread, if it helps you visualize it.

With the cocoon thread captured safely in my last three fingers, and the cocoon held loosely with forefinger and thumb, I flip the hand over, and drop the cocoon into the reeling water. When I turn the thumb side upward, the filament is on the tip of my index finger.

This is what it looks like when I've dropped the cocoon, and I have the filament on my finger. Emperor's Clothes, hey?

This is a close-up of the same view. Notice where you can see the filament crossing in front of the cocoon at the center bottom, and if your monitor resolution is good you can see the filament between my fingertip and thumb.

Here, I've got the filament on my finger, and I'm going to attach it to the reeling thread. I push the back of my fingertip against the reeling filament, and it just grabs the thread and joins it on. Don't let go with the thumb and other fingers; this will snap off the end neatly, leaving no visible mark where the thread is cast on. Once you get used to it, and if you have a good reel, you can cast on cocoons without ever slowing the reel.

This is what I'm reeling with these days. It's a custom design by Bill Wyatt, based on an antique Japanese silk reel called a Zakuri. The bobbin is accelerated by a series of pulleys and belts, and the arm in front rocks back and forth, so that the wet silk is not piled on top of more wet silk. It makes a HUGE improvement in the process over reeling onto the clock reel, because the rocker arm takes the place of my left hand, so I don't have to stop reeling to feed cocoons.

This is the antique Japanese version. The uprights are made of a soft wood, similar to pine, and the gears are carved from a hard wood called Zelkova. The bobbin is called an itomaki, and fits on a removable spindle so that it can be exchanged for a fresh one.

This is a major innovation in my silk reeling process, almost as significant as the improved reel. This is called a Tavalette, or Italian, croissure. Croissure means "crossing" in French - the filament is passed through a series of guides and pulleys such that it twists together with itself, thus squeezing out much of the water and agglutinating (gluing together) the filaments with sericin. The reeling pot is just out of the frame at the bottom right. The filament goes up, through a guide, over the top pulley, around the bottom pulley, through the croissure, and then through the upper guide eye to the reel. Croissure makes a much better quality of silk, because it is less likely to abrade or shred during processing. There is another type of croissure called Chambon, or French; it requires double reel and double cocoon setup, and one thread from each side is taken into the twist and then they separate to wind on to the reels. Note: the pulleys are laundry-line pulleys, they were around $3.50 each at the hardware store. They are mounted on my ever-present chemistry ring stands, but a dowel inserted into a wood block would work just fine.

This shows the actual croissure. The filament at the top right is not any thicker than the others, the flash is just catching it. I use about thirty twists; I find that if I use too many more than that, it snaps the filament more easily. Croissure drags on the silk slightly, so if there is a slub or weak spot, it will break the filament. If the filament breaks, you have to piece up.

This is how you piece up the raw silk filament. It's in the center there - it's an overhand knot with both strands, trimmed close. The ends need to be just a few millimeters long, or they'll snag later on.

This is a spool of raw silk. With the improved setup, I can make an ounce of raw silk (about 250 cocoons) in an evening's reeling. The bright spot is a dime for scale - the flash caught it.

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Reeled Silk

This is some of my reeled silk. The first couple of photos are mostly flat silk, which is totally untwisted. I use it for brocading fiber in my tablet weaving. This kind of silk is known as filament silk, flat silk, or soie platte. It is popular in certain kinds of embroidery and weaving, where its amazing sheen will be appreciated but it won't be abraded or put under tension. One major benefit of the flat silk for brocading, is that it will "belly out" - flattening on the surface of the woven fabric to make the brocaded design appear more solid.

The round spools are not the most practical way to handle the silk, but they show it off to best advantage because of the round shape. You can see the brilliant, lit-from-within sheen that only reeled silk can give, because the filaments are going around the curved shape.

These are bobbins of silk for a tablet-weaving project. The golden bobbin in the front is organzine, which is like a plied yarn - the filaments have been twisted in one direction, and then twisted back in the opposite direction with another strand. Organzine is stronger than the flat silk, and is used for warp and ground weft, as well as for many other techniques. The other bobbins are flat silk.

Here, you can see all of the flat silk and organzine put together for a project. This is for a tablet-woven ribbon, blue background with white lettering, a black border with gold spots, and green and brown brocade. It's the first project I've made entirely out of my hand-reeled silk. The blue, gold, white, and black are organzine; the little bobbins of olive and green are flat silk.

These blue spools are for a trade project. All of ones in front are untwisted tram, in shades of Jacquard Teal and Brilliant Blue.

The blue spools. The second and third from the bottom are organzine, the rest are tram. Top three are the Brilliant Blue, botom three are Teal.

A variety of colors on cards. This is a good way to store the thread so that it won't tangle.

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Silkworm Gut

Silkworm gut used to be the preferred material for making fly fishing leaders. It is flexible, strong, and very nearly clear; it's amazing that it's actually natural, it looks so much like plastic. PLEASE NOTE: This page shows the dissection of a silkworm for the gut; if you don't want to see that, please don't read on.

When they are just about ready to spin, having emptied out any undigested food, the worms are dropped into a solution of vinegar and salt. There are various instructions on how salty to make it, but one source says that it's basically as much salt as will dissolve, so that's what I did. The worm floats in the middle of the solution, which is kinda cool looking.

The worm's head is to the right. I've made a small incision in the back, right behind the head. The silk glands practically pop out. They feel soft, slick, and slightly rubbery - like cool hot glue.

I've always heard that the silkworm at the final stage is mostly silk - but it sure makes it dramatically clear when you see the silk glands separated out like this.

Each gland can be gently tugged and pulled out into a single strand, about 18 inches long. I'm not good at it yet, so I broke each strand into two by tugging it wrong. It's strange, how the strand has a pre-set size - you can definitely tell when the strand is stretched and won't stretch any more.

The stretched strands feel a lot like animal sinew. At this stage, they are whitish and opaque.

After drying, the strands clarify. I can see why a lot of the old fly-fishing gut was called "mist colored" - this has a slight blue-gray cast, but is clear like nylon monofilament line. If somebody handed me a strand of it, I would automatically assume it was plastic; they don't feel at all like silk.

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