Silkworm Care and Breeding Guide + Chow Preparation

[JeffreH]

A couple of members were interested in care and breeding articles on the Chinese Silkworm, Bombyx mori. These articles were NOT written by me, but by good friends of mine in the hobby Rob Talkington and Cheri Smith.

Unfortunately I do not have the original pictures that were associated with the articles but will work on obtaining them. In addition to this information, I invite anyone interested in culturing Silkworms as a food source to look check out the wormspit blog for a fantastic compilation of photos and information on rearing this species from egg to adult: Bombyx mori, the China Silkworm [may need to copy and paste link into browser].

Articles:


Silkworm Care (Part 1 - Raising & Housing Silkworms) ()
Published: June 18, 2005

Silkworm Care Part 1 - Raising & Housing SilkwormsBy Rob Talkington (Wideglide)
Caring for silkies is relatively easy. When you read this care sheet please keep in mind this information is from my own experience with caring for and breeding silkworms. There are many different techniques and what works well for myself may not work well for you, however I do believe if you follow some basic guidelines you can adapt a technique that suits your situation.
Basic Care (Silkworms over 3/8” in length)
Housing
So what are you going to keep your silkworms in? Well one of the great things about silkies is that if they’re fed well they really don’t do much of anything. They basically sit there waiting either for more food or for you to feed them to your animals. I use Rubbermaid type containers but some other options are small aquariums, critter keepers, disposable Glad containers or basically anything that has sides and a flat bottom. Use something big enough so the worms aren’t competing for floor space. If you see 4 silkies sit there on top of each other chances are you don’t have enough floor space. You don’t need to worry about any type of lid because, like I indicated above, they just don’t go anywhere. Now, I like to provide a surface the silkworms can get some grip on so what I do with my Rubbermaid containers is take some sand paper and scuff the bottom of the container a little bit. This seems to keep the worms from clumping together in a group, which in turn, makes it easier to pick them out to feed off. You can accomplish the same thing by lining your container with paper. Something new I’ve tried is taking a paper plate, turning it upside down and just placing the worms on the plate. When I need to get rid of their waste the majority of it has fallen to the edge of the plate. I pick the entire plate up with the silkies still attached and tilt it towards the trash and the waste just falls right off. If you decide to do this be sure to dump the waste onto another plate over the trash can so if any worms happen to fall you catch them instead of them falling into the trash.
Some articles I’ve read indicate you need to be ridiculous about keeping everything sterile and to wear rubber gloves when doing anything with the silkies. Some articles also say you need to move the silkies every few days into a brand new, sterile container. In my experience that’s just plain being paranoid. Never have I worn rubber gloves when doing anything with my silkies and I usually clean their container maybe 3 times during their entire lifespan. I’m not saying it would be smart to handle a pile of dirt then go feed your silkies I’m just saying there’s no need to go overboard with such things as rubber gloves.
Temperature
The temperature range that I recommend is anywhere from about 68F to 85F. The warmer you keep your silkies the more they will eat and the faster they will grow. The cooler you keep them the less they will eat and the slower they will grow. So if you've got too many silkies drop the temps, feed them less and hopefully they won't grow faster than you can feed them off. In my experience the bigger the silkies the less vulnerable they are to temperature extremes. Unless you have a very humid environment humidity is not really much of a concern with juvi silkies. With hatchling silkies that is a different story and is addressed in the breeding section of this caresheet.
Food
You can do one of two things here. You can either find a mulberry tree somewhere and feed your silkies it's leaves or you can purchase silkworm chow made from mulberry leaves. There are numerous places on the net to buy the chow. Unfortunately that's about it as far as food goes. I heard once that silkies can survive on other items but honestly I don't believe it. In a bind you can substitute leaf lettuce for a day or two if you happen to run out of chow but much longer than that and your silkies will die for sure.
When you handle the food it is advised that you only handle the food you are about to feed. Handling food you are going to put back in the fridge may contaminate the food and allow bacteria to breed. Not a good thing.
The amount of food you will want to feed really depends on how big the silkies are and how fast you want them to grow as well as the temperature you have your silkies at. When the silkies are smaller you can take a cheese grater and grate some chow right over the top of the silkies. Just give them a nice covering of food once a day. If you notice there is chow left over which is dried out you can place a piece of wax paper over your container to help retain the moisture. If you have chow left over from the day before it's a good indication you're feeding too much and you should cut back a little. With bigger silkies you can simply cut the chow into chunks or strips and place it in their container. You can do the same with smaller silkies but I find it's easy to over feed this way and it's easy to waste a lot of food. Feeding hatchling silkies is somewhat different and is discussed in the breeding section of this caresheet.
If you are in a humid environment and there is silkworm chow that is left over from the last feeding it is important that you let it completely dry out before the next feeding. This is to prevent any mold from forming which will kill your silkies. If you do notice mold, if it is relatively easy, you can move your silkies to a new container. If you have hundreds of silkies and this seems like a daunting task I have had success just moving the silkies off the molded areas and making sure to let everything dry completely out. When you feed just keep any food away from the area that previously had mold and keep a close eye on other areas concentrating on letting everything dry completely between feedings.
Part 2 of this article - "Breeding Silkworms" - is available by clicking here.
http://www.reptilerooms.com/Sections+index-req-viewarticle-artid-107-page-1.html
Article by Rob Talkington. Copyright Rob Talkington ©2005. Reproduced with Permission.
All images Copyright The Reptile Rooms ©2005 Unless otherwise stated.

[JeffreH]

Silkworm Care Part 2 - Raising & Breeding Silkworms ()
Published: June 18, 2008
Silkworm Care Part II - Raising & Breeding Silkworms By Rob Talkington (Wideglide)
Breeding Silkworms
With a little patience and practice breeding silkworms is fairly easy and the return is large enough that if you are successful with just a few mating pairs of silkworm moths you'll produce enough where you no longer need to purchase either eggs or silkies from a retailer.
The basic lifecycle of the silkworm is as follows. Keep in mind this is not a technical description detailing specific stages of growth for the silkworm itself, it is just a description of how it begins and ends for a silkworm.

• Eggs - First you've got a silkworm egg, which will hatch after about 3 weeks of incubation. The egg will start off as dark gray to black in color and just before the silkie hatches that egg will turn to a light gray and sometimes become transparent.
• Hatchling Silkie - When the newborn silkie hatches it is no more than about an eighth inch in length. This is a very delicate time for a silkworm so keep this in mind.
• Adult Silkworm - Depending on temps and food, in about 3 weeks, the silkworm can grow to as much as about 4" in length and be as thick as your ring finger!
• Spinning Stage - The silkworm will eventually stop eating, have one last defecation and then actually shrink some. When this happens it is ready to spin its cocoon. This spinning last about 3-5 days as long as the silkworm's cocoon is not disturbed while it is spinning. If it is disturbed the silkworm must start all over again in a new location.
• Cocoon - Again the time frame here depends on temperatures as well as other factors like how healthy the silkworm was when it created its cocoon. Anywhere from 3 to 6 weeks later and the silkworm will have mutated into a moth and the moth will break out of the cocoon.
• Moth - Once a moth hatches it looks for a mate of the opposite sex. The moths do not eat, drink or fly due to generations of domestication by humans. They mate, lay eggs then die in about 5 or 6 days.
• Eggs - Once again back to eggs. Once the moth lays the eggs they will be yellow in color. If they are fertile they will turn to a dark gray or black color. This is when you put them in the fridge. If they are not fertile they will remain yellow.

Eggs - Incubation and Hatching
When you are ready to incubate and hatch a colony of silkworm eggs you have a number of options. I use an incubator but have read of many people just having the eggs sit at room temperature and be successful. I do not know if their environment more closely matched that of what has been considered optimal conditions or not so I'll explain my method and you can choose to do what you think works best for your situation.
I usually place my eggs into a 5"(approx.) Petri dish. If they are loose I will take some Elmer's non-toxic stick glue and spread a thin layer on the Petri dish and sprinkle the eggs on the glue. Most of the time my eggs are stuck to small card of paper because of how I breed my silkies so rarely do I use the glue. If the eggs are on the card I just put the card with the eggs stuck to it in the Petri dish. I do not glue the card to the dish but that's just me, if you want to, go ahead and glue the card down.
I have the incubator set to 84 degrees and have a reservoir of water in the bottom to keep the humidity at about 75%. If you don't have an incubator one method I've read about indicates to put the Petri dish on something such as a kitchen counter and place a bowl over the Petri dish. Within the bowl place a moistened paper towel to provide the necessary humidity. Also place something under one edge of the bowl to allow for ventilation. You can apply heat in the form of a lamp if desired but keep an eye on the Petri dish to make sure it does not build up condensation inside. Condensation will drown the eggs and you won't be very successful.
The length of time for incubation will depend on the temperature as well as other factors. Usually my eggs will begin to hatch in about 3 weeks and will continue to hatch for about 3-5 days. Once the eggs begin to hatch you will need to provide food for the hatchlings.
Hatchling Care
So your eggs have begun to hatch and now you need to get them some food within 36 hours or they will begin to starve. Since there are still eggs that have not hatched it is important that you do not smother these unhatched eggs with the food. One method is to take a couple of tooth picks and place them close to the eggs. Cut a couple of tiny strips of chow and place the chow right on top of those toothpicks. The hatchling silkies will climb to the food as long as it is fairly close to them. It is important for the food to be near the hatchlings because at this stage they will not travel very far looking for food. They will just starve and die. Another method you can use is to just take tiny strips of chow and place them as close to the eggs as you can without smothering any. If you see any stray hatchling silkies you can take a small painters brush and move the strays onto the food. If you want to you can also just move all of the silkies as they hatch into an entirely different container and place your food there with them. Use a small paint brush to gently move the tiny silkies so as not to injure them.
Check on your hatchlings often to look for any strays or to see if you need to add any food. An important thing to look for is any mold that may develop. Since the eggs and hatchlings will be in a humid environment it is important that you keep a close eye on the food and that it does not become moldy. If you notice any mold simply take the container out of the humid environment and let everything completely dry out. When you notice you need to add food is a good time to take the container out for a few hours and let everything dry just to be on the safe side. Usually you will need to add food about 3 days into hatching but probably not much sooner than that. The tiny silkies do not eat a whole lot when they are this small and the strips are usually covered with a layer of silk and frass(waste) instead of being fully consumed. Keep in mind it may take several hours for this silkie, frass covered food to dry completely but it is important that it does dry out to prevent the formation of mold.
I use this routine until the worms are about 3/8" long then I move everything including the Petri dish into a new container where the silkies will spend the rest of their lives until they cocoon. This container is kept at room temperature or sometimes I will provide a heat source if I want my silkies to grow faster for some reason. If you want you can move the silkies themselves with a paintbrush to free up your Petri dish. From here, until the silkies are near the stage where they cocoon, follow the care information at the top under Basic Care.
It's Cocoon Time!
How will you know when your silkies are getting ready to cocoon? Well it can be tricky at first but soon you will be able to recognize your silkies behavior and appearance change when they are ready to spin their cocoons. First the silkworm will stop eating and be moving it's head in a figure eight fashion. What it's doing is beginning to spin a cocoon but sometimes they will get confused and begin eating again when in this stage. Next the worm will have one more defecation that will be really runny and not look like any other frass it has expelled before. It is getting rid of any waste to prepare for mutation. At this point the worm will not begin eating again and needs to be given access to a place to cocoon. You will also notice the silkie will actually shrink and become a yellow color that is somewhat transparent. Now the silkworm is full of saliva(silk) and again needs a place to spin it's cocoon. If you are unsure about being able to recognize when your silkies are ready to spin there's an easy way to make sure you don't wait too long. What you can do is have a new container ready with your cocoon setup but don't use the whole container. Save a small space you can place the biggest silkworms into and continue to feed and when they are ready to spin they will find the area you have set up for them to make their cocoons. What is that setup like you ask? Well it's relatively easy to setup an area for your silkies to cocoon.
The basic requirements for a cocoon ready setup include some sort of configuration where there are plenty or corners or walls where your silkies can attach their cocoons. This material needs to be something that holds the silk like cardboard(not the shiny kind). There are unlimited ways you can accomplish this setup. I have used strips of cardboard bent into many angles and wedged into the spinning container and that has worked well but my preference is to use empty toilet paper rolls. I feel it is the most efficient way in terms of the amount of space that is used.
Take your toilet paper rolls and cut them in half, lengthwise. In your container place these halves so that if you look down upon them it looks like you're looking through a wine rack. Basically you'll be looking at a bunch of circles. To help give support, take paperclips and clip the edges of some of the rolls together to give them stability. This stability is extremely important because once your silkies have started to spin their cocoons, if you make the slightest disturbance, unless the cocoon is almost finished, the silk worm will have to pick a brand new spot and start all over spinning it's cocoon. They're funny that way. Hopefully if this happens the silkie has enough silk stored up to finish a new cocoon. If not the silkie will just die in a half finished cocoon and you'll get nothing out of it.
It will take anywhere from 3-6 weeks for the moths to begin to emerge form the cocoons. After the cocoons have all been spun, if you want, you can remove the cocoon from it's original location and consolidate all of them into a different container. In my opinion this seem to effect the amount of moths that actually emerge as well as it can be a pain dealing with all the small strands of silk. I used to move the cocoons but now I just leave them as is and wait for them to begin to hatch. I always have cocoons that don't hatch and I'm sure you will as well.
Silkie Moths
The moths break out of their cocoons by excreting their saliva, which apparently has a dissolving effect on the silk of the cocoon. For some reason, and I cannot tell you why, a good percentage of moths never make it out of their cocoon. I don't know if this is because there were problems with the silkworm before it began to spin or what. I've tried different temps, humidity, etc. and have never been able to get all the moths to emerge successfully from their cocoons so plan on have some cocoons left that never produce anything. If you want you can take the cocoon to your ear and give it a little wiggle. If you don't feel any movement of anything in the cocoon chances are the moth has been created but cannot get out of it's cocoon. Then you can get a small pair of scissors and cut the cocoon open to let the moth emerge. I would only do this for feeding the moth off to one of my animals. I would not let this moth mate as you may only be passing on defective genes to the offspring. If, when you shake the cocoon, you hear and feel like there's a little marble or pebble in the cocoon it is still in the mutation stage and you should leave it alone.
When a moth does successfully emerge the first thing it might do is hang out until its wings fill with fluid or it may wander around looking for a mate. Males are more likely to wander around than females. When I have a moth emerge I put it into a breeding bin I have set up with small squares of cardboard. Be careful when moving the moths for a couple of reasons. One is that you don't want to injure the delicate wings and also because sometimes the moths will squirt a brown liquid substance from their behinds and it's really pretty gross. Just make sure you've got it's back end facing away from you the first time you move it. Usually the moths will only squirt this material one time. I think it's some sort of hormone but that's really pretty gross. An easy technique I've found to move the moths is to create a small strip of cardboard maybe about 2-3 inches long and ?" wide. Gently coax the narrow piece of cardboard underneath the moths legs. If you're gentle and make small enough movement the moth will eventually just move each leg onto the piece of cardboard. Once the moth is on the strip you can just lay end of the strip where the moth is on one of your cardboard squares so the moth is sitting flat and then with your forefinger push on the moths face away from you while you slide the strip of cardboard from beneath the moth's legs. Otherwise it can be somewhat difficult to get the moth moved without holding it by it's wings, which tend to rip apart easily.
Breeding Bin
What I do to set up a breeding bin is take a Rubbermaid type container that is about the same size as my other bins and place cardboard squares in the bottom. I cut squares of cardboard that measure about 2" x 2" and place them all over the bottom of the container. These squares will be where the moths mate and also where the female moths will deposit their eggs.
As stated above I place new moths into the breeding bin and wait for a male and female to "hookup". A female moth will usually just sit there with some sort of gland protruding from it's behind while the males will be wandering around flapping their wings very rapidly. I'm not sure if I mentioned this but the moths cannot fly. When a male and a female hookup they will be locked at their hind end and may stay that way for days. When I notice two that hookup I take the square of paper they are on and I place the mating pair into a smaller container that allows the cardboard square to lie flat on the bottom. I try to make the cardboard squares just small enough so that they do lie flat. This is so all of the eggs will be stuck to the cardboard and not to the small container itself. I just think it makes things easier in the long run. I just place this smaller container back into the breeding bin. If the female starts to deposit her eggs and the male still has some life left you can take the male out of the smaller container and back into the breeding bin to fertilize another female. Most moths will die after about 6 days and those that last longer might make it one more day but rarely have I seen any moths live past 6 or 7 days.
If you use the technique above the need to recognize male and female moths is reduced. The basic differences between the two are size and shape. The female moths will usually be bigger than the male moths. The female moths will have an organ protruding from their behind that they can retract as well. The male moths are usually smaller and instead of a protrusion have somewhat of a flap on their hind ends. I would suggest you use the method above to start out and learn to recognize the differences if you need to.
The female will lay anywhere from 200-500 eggs on the cardboard or whatever else you may be using. Once the female moth is done laying her eggs she soon dies. If you are planning on feeding the moths to your pets I suggest you wait until the female has laid all of her eggs. This is because I have seen undigested silkworm eggs in the feces of animals I have fed these moths to and I believe it presents an impaction risk. The males you can feed off whenever, once you are able to recognize them.
Eggs
When the female lays the eggs they will be yellow in color. If the eggs are infertile they will remain yellow but if they are fertile they will begin to change. At first they will become somewhat burgundy or brownish in color. After a few days they should turn darker until finally they will be a real dark gray to black color. I seem to notice a hint of purple as well. When the eggs reach this color it is time to put them into the fridge. I take a Ziploc baggie and just put the card with the eggs stuck to it into the bag and then I place that bag into a bigger Ziploc where I store all of my back stock of eggs.
There is some controversy as to whether it is necessary to cool the eggs down before you attempt to incubate and hatch them. Frankly I've seen them hatch even if they skipped the cool down period but I've also seen them fail to hatch without a cool down period. Rarely do I have any eggs that do not hatch if they've been cooled so I would say your best bet is to put them in the fridge for some time before trying to incubate them. I believe there is a much better chance for success if they are cooled first. How long should they be cooled? Honestly I have not kept that detailed of records as to how long they were cooled before I pulled them out to hatch so I can't comment on that. I can tell you with me it's usually been a minimum of a few weeks before they have been brought out to hatch. Supposedly the eggs are good in the refrigerator for up to 5 years.
When you're ready to start a new colony take a batch of eggs out of the fridge and begin to incubate them. That's pretty much all there is to breeding except for one particular problem I have every once in a while and have had no luck figuring out what causes it. After the eggs are laid, if they're fertile, they're supposed to go from yellow to brown then to dark gray or black. This is when you're supposed to put them in the fridge. For some reason I sometimes have eggs that just won't cooperate and skip the change from brown to dark gray/black. These eggs go from yellow to develop a small black dot towards the edge of the egg and then go straight to light gray and hatch!! One time I had this happen unexpectedly and I had thousands of baby silkies I hadn't intended to hatch yet. I wish I could tell you how to prevent or maybe even provoke this to happen but I can't seem to find a constant factor that is different from normal.
I'd like to point out again that the information above is only what I have found works well for me and should only be used as a guide. If you follow some of the basic requirements and watch out for things like mold you very well may find a different technique that works better for you. Also, I am always interested in new ideas so if you have a technique that works well please feel free to share it with me. My username in The Reptile Rooms is wideglide and I'm always willing to answer any questions as well. I hope this information has helped you become successful raising and/or breeding silkworms.
Part 1 of this article - "Raising & Housing Silkworms" - is available by clicking here.http://www.reptilerooms.com/Sections+index-req-viewarticle-artid-100-page-1.html
Article by Rob Talkington. Copyright Rob Talkington ©2005. Reproduced with Permission. All images Copyright The Reptile Rooms ©2005 Unless otherwise stated.

[JeffreH]

Silkworm Chow Preparation ()
Published: June 18, 2008
SILKWORM CHOW PREPARATION
Images show Microwave cooking
Ingredients

• 1/2 lb Silkworm Chow Powder
• 3 Cups of Water (use distilled or spring water)

Cooking in Microwave

1. Mix the water and powder together in a micro wave safe container and stir until all is dissolved completely
2. Cover with a piece of Saran or Plastic wrap that is safe to microwave.
3. Cook on high for 3 minutes, (may need longer if you have a low watt microwave) it should just start to bubble
4. Remove and stir really well till it is a think consistency. (be careful to avoid the stream coming from under the plastic wrap)
5. Recover with the saran wrap and return to microwave to cook for 3 more minutes
6. Remove, stir and replace the saran wrap, pat it down with a hot pad through the plastic till it is even all the way around and let cool
7. Once cooled it will set up and you can cut into smaller squares or just cut off the amount you need to feed the worms.
8. Refrigerate till needed, it will keep about 1 month in the refrigerator, but you may also freeze some and take out as needed to thaw

Stove Top Preparation

1. Heat the 3 cups water till it starts to boil, add chow, you need to stir constantly until it reaches a full boil. (chow can burn easily)
2. Remove from heat,, cover with saran wrap, plastic wrap or wax paper.
3. Press down on the chow through the paper using a heat pad or glove till it is level.
4. Set to cool, when cooled you can cut into squares or cut as much as you need and refrigerate the remainder.
5. Chow will keep refrigerated for about a month, but may also be frozen and thawed as needed

NOTE: CHOW SHOULD HAVE THE CONSISTENCY, WHEN COOLED, OF BLOCK CHEESE - may need less water in the microwave
CUT INTO SMALL SLIVERS OR GRATE OVER THE WORMS TO FEED THEM.
Article by Cheri Smith
Copyright Cheri Smith, The Reptile Rooms ©2005
All images Copyright The Reptile Rooms ©2005 Unless otherwise noted.


*Again, I want to thank Rob Talkington and Cheri Smith for this literature. And my good friend Ashley (Cammy) for salvaging this information.

I'll add some additional information to this thread from my experiences with time and would love if anyone else would be willing to share their tips and tricks and culturing this species as well! There has been a little bit of previous discussion in this thread:
http://www.frogforum.net/food-feeder...bt-staple.html

[JeffreH]

Nutritional Information:

Silkworms - The Benefits of feeding your reptile and pet the silkworm

The Feeders - BambooZoo [Good comparison of a variety of feeders]


I'd like to add that Silkworms also contain the enzyme serrapeptase which has properties that increase calcium metabolism, and also reduce pain and arterial plaque. This properties have been validated by Cheri Smith using silkworms on rescued bearded dragons to my knowledge. Overall, Silkies are incredibly soft-bodied, very high in protein, and low in fat. They are arguably one of the most nutrionally sound feeders available...but as always, variety is the best for any herp.

And just a couple of additional side notes: I have had immense die-offs from mishandling chow and larvae... while the article claims that disinfection and sanitary practices aren't as necessary as typically recommended, I would prefer to err on the side of caution and sanitize your hands before working with the larvae. They are incredibly prone to bacterial infection and disease and spread like wildfire amongst cultures (Mulberry Farms has an unforunate experience with this, amongst others).

In addition, another tip I have to offer is to use plastic canvas grating for the larger larvae or later instars... the #7 grating allows frass (poo) to fall through the holes while keeping your silkworms clean and happy. Simply elevate the canvas with something in the bin and keep the food and larvae centered... they don't move around much ; )