Intro#

I started this project for fun and because there is a mulberry tree growing in my backyard. The project started on May 6th and finished just after the last silkworm completed its lifecycle on August 2nd.

Here in unincorporated Silkworm City you will learn all about the silkworm life cycle, their eating habits and much more…

There’s two ways to experience the story of Silkworm City. One is through my story below and the other is through a timeline of pictures and videos.

Let’s go!

My Silkworm Experiment#

The silkworms started as tiny itty bitty black eggs. I put them in a Petri dish under a reddish orange light for heat and with a top on to create humidity inside the dish. My dad let me borrow his thermometer so I could make sure it didn’t get too hot or too cold inside the Petri dish. I was trying to keep the temperature at 83°F.

About 5 days after starting the project, the eggs turned a grey-white color and then they started to hatch!

When the silkworm caterpillars (larvae) first hatched they were black and so small I couldn’t tell if they were alive or dead. So I ran outside to my tree and picked a fresh leaf. I cut the leaf up into little pieces and I placed them in the Petri dish. I saw that they started eating the leaf so I knew that they were alive.

So far, the project was a success.

As the days passed, more and more silkworms hatched. I started leaving a breathing gap between the top and the bottom of the Petri dish. I checked them a few times a day and gave them food as needed.

About day 7, so many silkworms had hatched that I moved the Petri dish into a container and kept the heat source. I also started giving them full leaves and no longer needed to cut the leaves up for them.

Their color started changing from black to a brownish color. They grew bigger each day. Soon their heads started turning white and their bodies lightened in color.

As the days passed the silkworms grew and grew and grew.

And as they grew they ate and ate and ate and ate and ate…

And ate some more.

And as they ate, they pooped.

Their poop is medicinal! But I will get more into that later.

About day 14, I moved them into a shoe box with a lid with breathing holes but no heat lamp.

When I would go to check on them, I would usually have to give them a fresh leaf since the old leaf had dried out by then.

The leftover leaves made such pretty patterns when you let the sun shine through them, but I forgot to take pictures of this so use your imagination.

As they grew and ate and pooped their habitat needed to be cleaned regularly in order to prevent mold from growing.

Mold is one of their enemies. I lost one silkworm caterpillar to mold. He was one of the smaller ones and got lost in the leaves as they piled up and their city had not been properly cleaned for a few days. I tried to save him when I found him and realized what had happened, but it was too late. He did not survive.

Here is a quote from some research I found about other enemies of the silkworm…

Silkworms are very sensitive creatures and need protection from insects, flies and environmental hazards. Mosquito nets are often provided for protection from flies and lizards. The uzi fly is one particularly destructive insect which lays eggs on silkworms. The larvae then feed on them, killing the silkworms.

My Silkworm City was set up indoors so mold was the biggest enemy my silkworms faced. That and hunger.

They were eating so much that I decided we should weigh the leaves before I fed them as the leaves from the mulberry tree grow to all different sizes. Counting how many leaves I picked each day to feed them didn’t make as much sense as weighing them and keeping a running total of the weight.

I wish I had thought of this earlier…

I started weighing the leaves on June 3rd which was 29 days into my experiment. My dad let me borrow his scale and I used a plastic container to hold the leaves as I weighed them because this was easier than trying to stack the leaves or weigh them one at a time.

I learned how to tare the scale so that the weight of the container was not added to the weight of the leaves. Please see the graph that I made of the weight of leaves in grams that they ate daily.

I also did the math to total up how much weight of mulberry leaves they ate all together. 506 caterpillars ate approximately 22.06 pounds of mulberry leaves during the time that I used the weighing the food technique to track how much they ate.

It was also around this time that I moved them into new housing, a large cardboard box with no cover. Also they were really looking like all the pictures that the books and internet show.

A friend of mine thinks they look like little space shuttles: their black heads, whiteish grey bodies and their ‘fake eyes’ which would be the front window of a space shuttle. I think those unique markings on their back must be where their wings come in when they become moths. Their fake feet, the back ones, are so sticky that I could put one on my hand and turn it upside down and they could hold on. I didn’t do this for too long or too often, but had to test it out a few times.

My silkworm caterpillars were eating and growing so fast! They ate so much that you could see the change in their size from morning to the evening. If I was quiet enough I could hear them munching so much that it sounded like rain on the roof or a rain stick. They were eating machines.

They eventually will grow to 10,000 times their original size at hatching. The speed that they go through their instars seems to vary depending on, I guess, the weather, season and how much food they could eat. I actually had to separate them into 3 groups of large, medium and small so that the smallest ones had a fair chance at getting food. This separation by size seemed to help as the little ones started to catch up in size.

I wanted to see how heavy they were getting. I looked for the longest and the fattest silkworm caterpillar and weighed and measured them. Measuring them was hard because they kept wiggling around trying to find food so getting an exact length and width was difficult. The heaviest silkworm caterpillar I weighed was 4.4 grams. I also weighed the smallest one I could find and it was so little still it didn’t even register on the gram scale. The longest one I was able to measure was just under 3 inches long.

I could tell when they were going to start spinning silk because they turned a translucent yellow color. I had been collecting toilet paper rolls and cutting them in half for the silkworm caterpillars to spin their cocoons in. I also used the bottom part of egg cartons. When I knew they were about to cocoon I would move them into a toilet paper roll or egg carton but they did not always behave. Sometimes they would move and cocoon in a corner, underneath the egg cartoon which was bad because this caused problems when they needed to hatch. Sometimes they rolled themselves up in a mulberry leaf. One even tried to cocoon on the dining room wall but it did not succeed because the surface was too flat so I moved it to a better location.

The silkworm caterpillars make their silk by spitting liquid out from their stomach and when it hits the air it becomes the silk thread. That is why they have to stuff themselves full of mulberry leaf before they start their spinning silk phase.

The cocooning process takes about one day and then they are in their cocoons for about two weeks before emerging as a silk moth. Sometimes two silkworms will cocoon together. A male and a female will cocoon together. They usually do not come out of the cocoon when two cocoon together. We read that when they double up the female will lay her eggs inside the cocoon but from the one we cut open we did not find this to be the case.

When the male silkworm moths emerged from their cocoons they are highly energetic and on the search for a female. They flap their wings like crazy, but do not fly, trying to get to a female first so they can get ‘married’ to her. Some male moths in their cocoons would shake around when they knew a female silkworm moth was emerging near by. Other male silkworm moths once emerged, if all the females silkworm moths were already ‘married’, would seek out a female cocoon to sit on and wait for her to emerge.

Female silkworm moths, when they emerge, just sit there and wait for a male to come along. The female silkworm moths have a larger abdomen and bigger wings, but smaller and less fancy antennas. The females display their energy when they are laying eggs and they do not want to be disturbed once they start laying. The female silkmoth can lay between 200-500 eggs. The eggs are yellow when they are first laid and then they turn a purplish color and then they turn black.

The smallest cocoon made was 7/8" in length. We thought the silkworm caterpillar was too small to cocoon but I guess he wasn’t. He did emerge successfully.

The largest cocoon was 1-1/4" long and it was a double silkworm caterpillar cocoon. They did not emerge successfully. In total, I had 23 unsuccessful cocoons where the moth(s) did not emerge.

Taking a cocoon apart was like unraveling a very thin, but very strong ball of yarn. It broke in a few places and wasn’t always the same thickness but I was able to unravel one. I wound it around a pencil of mine. The silk thread is incredibly strong yet flexible and so soft. The silkworm moths are also incredibly soft and furry.

When the silkworm moths have lived out their life you can keep the nice looking ones for your bug collection, which I did. I also gave some to my friends to start their bug collections. If you have chickens you can feed them to your hens. They will enjoy the moths as well as the exoskeleton from the pupa that you remove from the cocoon once the silkworm moth as emerged. No waste!

And so there it is… the story of my experiment and experiences with my Silkworm City!!! This is the end of my story but the beginning of my research. Please read on to learn more about my silkworm research and the industries these insects support. Enjoy my drawings, photographs and videos and be sure to check out the timeline. Hope you learn something and have some fun. On that note, I am going to leave you with 6 fun facts, one for each leg of an insect! But you have to read to the bottom to get there…

The Discovery of Silk#

The history about the discovery of the silkworm cocoon took place in China around 3000 BC by the empress because one fell into her tea. She noticed that it started to unravel and how soft and strong the thread was. The tree near by was a mulberry so she made the connection and then she made a request to have mulberry trees planted throughout the empire. She had the first silk factory created as well.

Types of Silk Production#

There are two types of silk production. One kills the pupae in the cocoon and the other lets the silkworm moth emerge and live out its full life cycle or destiny as GOD intended. The silkworm can contribute to so many industries it is a shame and shortsighted to not support the no kill silk industry. This industry is known as Ahimsa. When looking for silk products please look for Ahimsa on the label and support life.

Silk Cocoons For Beauty#

The silk cocoons are not just for making silk, they are also popular for beauty. The cocoons are used for facial health. You put one on your finger, get it wet with warm water and then massage your face in tiny circles to remove the dead skin. It is suppose to remove wrinkles too.

It feels super soft and really nice. It was easy to use in the shower and also helped get all the dirt off my face after playing outdoors. If you want to get dead skin off your face I recommend the silkworm cocoon. Sericin is the protein found in silkworm cocoons that has many uses for beauty and medicine. Here is a link so you can read more:

Read about using silkworm cocoons for beauty.

Oh, I almost forgot… my mom thinks that the meconium the silkworm moth releases likely was one of the original forms of foundation, which she says is make-up some women use to make their skin look nice, like they are not wearing any make-up if that makes sense. She tried using it on her hand one day after it had dried and said it applied just like a foundation powder. That is seemed to blend well into different skin tones and that it made her skin really soft and silky. But when we looked we were not able to find any research supporting this theory of hers.

Silkworms in Art and Literature#

Silkworms have also made their way into books and art. We just read “James and the Giant Peach” by Roald Dahl and guess who one of the heroes in the story is…? A silkworm! I don’t want to ruin the story for those who haven’t read it, but I must say this, it is not a real portrayal of a silkworm because he never became a moth.

We also found a stamp from Lebanon that featured the silkworm caterpillar, cocoon, silkworm moth and the mulberry leaf. The silkworm has obviously been very inspirational to many artists around the world.

Silkworm Lifecycle#

The silkworm goes through a complete metamorphosis. The silkworm caterpillar goes through 5 different phases called instars. Each time they go through a growing phase they molt, though their first few molts were so tiny I really couldn’t find the shedded skin easily if at all. After each molt they enter into a new phase or instar. After the 5th instar, they cocoon and enter the pupae phase. Eventually they emerge as a silk moth and start searching for their mate.

Oh, and the coolest thing is before they molt they do this pose where they raise their head and their six legs, their real legs, up into an upward dog-like yoga pose. This is their meditation time and a really bad time to disturb them. See my diagram for more information on instars.

Rate of Leaf Consumption#

My silkworm caterpillars ate about 22.06 pounds of mulberry leaves before they were all in cocoons.

Below is an area chart my dad showed me how to make with Charts.css.

Silkworm Taxonomy#

In science this year I learned about Carl Linnaeus and how he developed the classification and nomenclature system of living things in the 1770’s.

Here is a little saying to help remember the classification system:

“Dear Katie, Please Come Over For Great Snacks!”

This is how the silkworm is classified:

• Domain: Eukaryota (organisms composed of one or more cells containing visibly evident nuclei and organelles)
• Kingdom: Metazoa (Animal Kingdom)
• Phylum: Arthropoda (have jointed appendages and a chitinous exoskeleton)
• Class: Insecta (Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae)
• Order: Lepidoptera (order of insects that includes butterflies and moths)
• Family: Bombycidae (family of moths)
• Genus: Bombyx (silkworm moths)
• Species: Bombyx mori (silkworm moths that feed on white mulberry leaves)

The silkworms ate so much over the next 20+ days that it became exhausting having to feed them every few hours. My dad had to start cutting branches off our mulberry tree and bringing them inside our home.

Silkworm Anatomy#

Here are my illustrations of the silkworm anatomy as a caterpillar and a moth.

Silkworm Medicine & Food#

Just to remind you I am eight years old and none of this is medical advice, it is just my research.

Nothing goes to waste when it comes to silkworms as the mulberry tree is medicinal and all parts of it can be used for medicine and/or food.

Let’s explore…

Mulberry Leaves#

The mulberry leaf is good to eat! Not just for the silkworm caterpillars but for us humans too: as well as for our bunnies, chicks, chickens and our friendly neighborhood squirrel Chad - everyone enjoys chopping down.

The white mulberry leaf is called Mori Folium, (sang ye in Chinese medicine), and is used to treat all sorts of health disorders like fever, dry lungs and cough to name a few. Overall it moistens and cools so no wonder it is a good summertime food for many animals.

So once the leaves are gone what is left? The branch!

Mulberry Branch#

What good is the branch? Now my bunnies love to strip the bark off the branches but the branches can also be used as medicine for humans. Sang zhi or Mulberry Twig/Morus Twig is good for treating pain in the joints, especially in the upper limbs, meaning your arms. It is also combined with other herbs to direct their energy to the upper limbs.

It is best to let the mulberry branches dry out and age before using them as medicine.

Mulberry Fruit#

Mulberry fruit is very yummy but my tree doesn’t have fruit since it is a male tree. Mulberry fruit, sang shen, helps relieve constipation, is very nourishing and helps greying hair regain its natural color which is something I don’t have to worry about yet. I wish my tree was a female tree because I would eat all the fruit possible and freeze what I couldn’t eat to eat later. Mulberry fruit is so delicious!

Silkworm Poop#

Remember when I told you that silkworm poop is medicinal… Well this is what it can treat. Can sha, or silkworm feces, is good for treating pain, tremors, paralysis, itchy rashes, cramps after vomiting and, or diarrhea and other things. You want to collect the poop after the 2nd or 3rd instar. It can be used internally or externally.

Sick Silkworms#

A sick silkworm is also used in Chinese medicine. Bai jiang can, is a silkworm that gets sick from the fungus Beauveria bassiana right before it gets to its silk spinning stage. The silkworm gets sick and the fungus infects the whole body killing them and making the silkworm look like a white mummy.

Bai jiang can stops spasms and convulsions especially in children. It can treat facial paralysis too. It also is used to treat seizures, which I learned are different than convulsions. Both are scary, but this medicine can help both issues.

Silkworm Pupae#

Now some people find the silkworm pupae to be tasty eating for fun. I don’t think this is my kind of delicacy but many love it. This means the silkworm has to be taken out of their silk cocoons before they change into a moth. You could have a silkworm caterpillar business with a restaurant on one side and a silk fashion house on the other. One business with two revenues. That’s a great investment!

Silkworm Genetics#

This might possibly be my favorite topic regarding my Silkworm City… experimenting with silkworm caterpillars and what kind silk they can make!

Silk Color#

White is the most common color a domesticated silkworm will spin its silk, but there are experiments taking place making the silkworm caterpillar spin either pink or blue or green silk.

Silk spun a certain color holds that color better then if you dyed the silk after it was spun. Some researchers are feeding the silkworms dyed food the last several days before they spin their cocoon to change the color of the silk they spin, while other researchers are changing their DNA so they spin a color different than white.

My personal feeling is that no animal should be eating chemical dyes as they are bad for the body. My mom won’t let us eat anything with chemical dyes, and you also should not be messing with GOD’s creations.

My solution would be to feed them mulberry leaves dyed with natural dyes like beet juice, berry juice, carrot juice, teas, turmeric or algae, just to name a few thoughts of mine. I have not seen any research on that yet… maybe I will do that next time.

I found out that the color in yellow silk comes from 6 different carotenes, the same pigments in carrots. These carotenes are found in the sericin layer of the silk filament.

A gene known as ‘yellow blood’ or Y gene enables silkworms to extract the yellow-colored carotenoids from mulberry leaves.

The Y gene encodes the amino acid sequence of the carotenoid-binding protein (CBP).

If there is a mutation in the Y gene, the silkworms won’t be able to absorb carotenoids and will produce white silk.

Silk Strength#

Some scientists tried to genetically modify the silkworm to produce stronger silk. They did this by changing the DNA of the silkworm to include DNA from the spider. Their experiment was a success! The genetically modified silkworms produced silk that was even stronger than spider silk.

More Info#

In my references, I include links to articles we read that discuss topics I did not have time to go into in this project. Soap, sutures for surgery and more. I encourage you to browse through them if what you have read so far has entertained you. These creatures may be tiny, but they hold so much potential in their life force.

Biblical References#

It’s so amazing how GOD has created everything for just about every purpose! Here are just a few of my favorite passages from the Bible that apply to my experiment and research.

Genesis 1:24

“And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.”

Genesis 1:25

“And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.”

Genesis 1:29

“And God said, Behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat.”

Genesis 1:30

“And to every beast of the earth, and to every fowl of the air, and to every thing that creepeth upon the earth, wherein there is life, I have given every green herb for meat: and it was so.”

Genesis 1:31

“And God saw every thing that he had made, and, behold, it was very good. And the evening and the morning were the sixth day.”

Proverbs 31:22

“She maketh herself coverings of tapestry; her clothing is silk and purple.”

Fun Facts#

1. Alongside bees, silkworms are the only other insect humans have domesticated. They have been domesticated over the centuries and selectively bred to spin cocoons that are whiter in appearance as white silk is easier to dye then the natural wild yellow cocoons.
2. The silk that silkworms produce is one of the world’s strongest materials. 
3. The silkworm, Bombyx mori, is named after the mulberry genus Morus – due to it being it’s main food source!
4. The worms shed its skin 4 times throughout its life as a silkworm - these phases are called instars. An instar is a developmental stage between molts, and a molt is when the larva sheds its skin. There are 5 instar phases.
5. The process of raising silkworms to produce silk is called sericulture or silk farming. The mulberry silkworm is responsible for over 95 percent of all the silk produced in the world.
6. The cocoon is made of a thread of raw silk from 300 to about 900 meters (1,000 to 3,000 feet) long. About 2,000 to 3,000 cocoons are required to make a pound of silk (about 0.4 kg).

Credits#

Dictated by: Jett Lee
Typed up by: Mom
Assembled into a website by: Jett Lee & Dad
Illustrations by: Jett Lee
Photographs & Videos by: Jett Lee & Mom

References#

https://www.madeinitalyfor.me/en/info/lantica-e-nobile-arte-serica
https://colnect.com/en/stamps/stamp/219231-Silkworm_Bombyx_mori_with_Caterpillar_and_Pupa-Silk_Congress_of_Beirut-Lebanon
https://discoverplaces.travel/en/legend-and-stories-about-silk-and-china-and-the-noble-art-of-sericulture
https://academic.oup.com/jinsectscience/article/17/5/105/4560634
https://www.theguardian.com/environment/2008/nov/17/network-food
https://lalouettesilk.com/blog/how-is-silk-made/
https://joannarosetidey.com/silk-worm-development-care/
https://www.sciencedirect.com/science/article/pii/S0143720815003125
https://www.abc.net.au/science/articles/2007/05/09/1918281.htm
https://www.muezart.com/blogs/muezart-musings/how-do-we-get-red-eri-silk-cocoons-what-causes-the-red-color
https://e-insects.wageningenacademic.com/bombyx_mori
https://www.cabi.org/isc/datasheet/9514#totaxonomicTree
http://www.thesilkroadchina.com/fact-v8-facts-about-silk.html
https://biblehub.com/topical/s/silkworm.htm
https://everythingsilkworms.com.au/10-interesting-silkworm-facts-will-blow-you-away/
http://www.suekayton.com/Silkworms/science.htm
https://joannarosetidey.com/silk-worm-development-care/
https://lalouettesilk.com/blog/how-is-silk-made/
https://academic.oup.com/jinsectscience/article/17/5/105/4560634
https://www.sciencedirect.com/science/article/pii/S0143720815003125
https://phys.org/news/2011-03-silkworm-diet-silk-medical-advantages.html
https://www.entomoveproject.com/blog/2018/04/15/silkworms-drinkable-beauty-product/
https://greenerlifeclub.com/advanced-soap-making-silk-worms-making-silk-soap-bonnie-garity-the-good-earth-spa/
https://www.treehugger.com/new-silk-production-technique-does-not-require-killing-worms-4858556
https://www.the-sustainable-fashion-collective.com/2015/08/18/how-is-silk-fabric-made/
https://www.muezart.com/blogs/muezart-musings/from-cocoons-to-threads-how-to-rear-different-types-of-silkworms-and-weave-them
Chinese Herbal Medicine, Material Medica 3rd Edition by Dan Bensky, Steven Clavey, Erich Stroger with Andrew Gamble, copyright 2004 by Eastland Press Inc.