How can I tell if my silkworm cocoons are dead or not?

#1
I have tried to do extensive research on this topic but I cannot seem to find a definitive answer on it. All I have found is as follows, pulled from a website I came across:

"Inside the cocoon, the silkworm sheds its skin and turns into a brown-shelled pupa. Inside this shell, the pupa turns into a moth. This process takes three weeks, and then the moth emerges from the cocoon. They usually emerge at dawn. The adult moth has a special spit which is used to dissolve the silk so it can push its way out of the cocoon. Silkworm farmers kill the moths before they emerge and make holes in the silk thread. When they emerge, the wings are crumpled, but they get pumped full of fluid and harden it about an hour."

According to the exerpt, the cocoons should hatch in about 3 weeks.

But not all of mine did...

Last summer I was raising a bunch of silkworms and 37 of them started to cocoon around early September. I had a bunch of toilet paper tubes for them to cocoon in and once they all finished, I waited about a week before I took them out of the toilet paper tubes and put them into a container to prepare them for hatching. All but 10 of them hatched in a couple weeks though. I still have those 10 in the container but they still have not hatched since September 2017. This was my first go at raising silkworms and I never had any of the worms die like so many people do (thanks to lots of good info I was able to gather from this site), but once I had cocoons in-hand, all but 10 of them hatched, and I am stumped on how to tell if the remaining ones are dead or not.

Now, I am very familiar with hornworm pupa which can lay dormant for very long periods of time. Those typically hatch in a few weeks as well but I've had some lay dormant for months before hatching, and I have had this happen on more than 1 occasion. The way you can tell if THOSE are dead are not though is by slightly squeezing their shells. If the hornworm moth is still alive inside of the pupa, then you will see the shell wiggle just a bit when you squeeze it, and the pupa shell will still be quite hard. If the shell is soft and no movement happens when you squeeze it, then the hornworm is dead.

The same cannot be said for silkworms though. You cannot perform the squeeze test on it because there will never be any movement of the casing due to how they spin their cocoons. Furthermore, the shells have always appeared hard in my experience. I would think that at LEAST 1 of my 10 cocoons would be dead but all of the cocoons are still super hard like they were just spun. One thing I HAVE noticed though is that when you give them a slight shake, some of them appear as if nothing is inside of them besides air and you cannot hear anything, and others sound like there is something small inside the cocoon that is shaking around, such as a small rock (obviously not a rock, but that's what it sounds like). I do know that when they begin to emerge, the ends of the cocoon will turn brown as they spit on it to soften it up in order to come out. But none of the 10 that I have left are brown on the ends, indicating that the moths never attempted to come out (at least not yet)

So, is it possible they are dormant like a hornworm can be, or are they most certainly dead by now?

I have attached a pic here so you can see them. They still look just as fresh as the day they were spun (minus a few eggs on one of them from when a female decided to start laying eggs before I was able to get home from my job and contain her handywork...)
 

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#3
What a bummer. Thanks for the prompt reply Matt. I've been holding onto em all this time in hopes that a dormancy period existed with them too.... lol. My panther chameleon loves the lil things!
 
#5
You could always carefully cut them all open and see what’s going on inside and how far they progressed. . .
Sounds like an episode of Dexter :ROFLMAO::LOL: but that was actually my plan if they were all gone for sure. This weekend I will because I am curious as to how far along they were. (y)
 

bobcochran

Chameleon Enthusiast
#6
You should leave the cocoons where they were spun, don't move them or shake them. This is most likely why some did not survive. When I get moths I like to put them in a brown paper grocery bag that has the top half cut off they spin their cocoons in there and I leave them until they emerge. I found I get a better adult moth rate this way.
 
#8
Hi, I used to raise silkworms for fun in South Africa. This was to show the grade 2’s the lifecycle of the silkworm. If you either unwind the silk ( a long and slow process) or carefully cut the cocoon open the silkworm (pupae) will not die. You can then put them into uncooked oats to keep them warm. You can then see them through the brown chrysalis and they wiggle if you touch them. Hope this is of some help. Good luck.

Sally Titch
 

celeste_knitter

Chameleon Enthusiast
#9
Hi, I used to raise silkworms for fun in South Africa. This was to show the grade 2’s the lifecycle of the silkworm. If you either unwind the silk ( a long and slow process) or carefully cut the cocoon open the silkworm (pupae) will not die. You can then put them into uncooked oats to keep them warm. You can then see them through the brown chrysalis and they wiggle if you touch them. Hope this is of some help. Good luck.

Sally Titch
That is very cool! I might have to try that sometime!
 
#11
Hi, I used to raise silkworms for fun in South Africa. This was to show the grade 2’s the lifecycle of the silkworm. If you either unwind the silk ( a long and slow process) or carefully cut the cocoon open the silkworm (pupae) will not die. You can then put them into uncooked oats to keep them warm. You can then see them through the brown chrysalis and they wiggle if you touch them. Hope this is of some help. Good luck.

Sally Titch
Are you still in South Africa? That is where I am from!
 
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