As usual, I learned a
lot about silkworm management over the past
week, had some growing pains, but am still looking forward to
further observations.



Chicken taste test

I read one report
stating that chickens love silkworms up until they’re two inches long, but I
wanted to get a more solid idea of the preferred size.  So I
froze fourteen silkworms every other day for a couple of weeks,
thawed them all out, and waited to see what the chickens
thought.  The answer?  Yuck!  Both my flock and I
decided that thawed silkworms are pretty nasty, and we didn’t want
to touch them.



Luckily, I know that
chickens love silkworms because I’d given dozens to our broody hen
before the taste test.  However, I still don’t know if
there’s a size at which silkworms become significantly less
palatable because all silkworms are apparently
unpalatable when frozen and then thawed.  I’ll have to figure
this out during round two of our silkworm project.



Red mulberry leaves

Ever since learning
that I’m experimenting with silkworms and that they’re voracious
eaters, one of my friends has been hunting down local mulberry
leaves for me.  It turns out he has two red mulberries right
along his driveway, and I took a few leaves home to see if our
silkworms liked them.  My caterpillars replied, “Yum!”

It was good to have a
supplemental source of mulberry leaves during our caterpillars’
last week because our primary tree is looking pretty bare, as you
can see above.  Although I didn’t provide red mulberry and
Illinois everbearing mulberry leaves side
by side, the speed with which our silkworms moved onto the
former suggests that they liked them at least as well as the
latter.  Red mulberry leaves are much larger and much more
tender than Illinois everbearing leaves at maturity, which makes
the species a good choice for silkworms.  Red mulberries are
also easy to grow from seed and are well-suited to our climate, so
I’ll definitely be planting some soon.



Cocoon-spinning

According to the book
I read, silkworms are supposed to spin their cocoons at about 25 or 26 days old. 

However, I learned the hard way that the short time frame is only
relevant if you never let your silkworms go without fresh
leaves.  In the real world of backyard silkworm culture, they
will take considerably longer to mature, depending on how well you
care for them.  And, yes, some will die — I lost a few of
my breeders
in their last week when they started to get a yellow cast, then
just keeled over.  (Hopefully we’ve got enough left that we
won’t end up with a genetic bottleneck.)



Anyway, our first
silkworm began to spin on day 35, with others slowly joining the
club over the next three or four days.  I’d read that you
need to add either the bottoms of egg cartons, toilet-paper rolls
cut in half, or sticks for the silkworms to spin into, and we
chose the first because we’re chicken-keepers and always have egg
cartons on hand.  I assumed our silkworms would spin in the
egg cups, and a few did, but most seemed to prefer the darker
crevices underneath the carton.  Those who did spin in the
cups chose ones covered by mulberry leaves.

When a silkworm
begins to spin its cocoon, it seems to just be wandering aimlessly
in circles.  After a couple of hours, a transparent cocoon
begins to form, like the one shown in the first photo in this
section.  The silkworm keeps layering on more silk into the
inside of the cocoon until it has finally formed a solid white
structure like the one shown below.  (The black dots are
frass, aka poop, from other silkworms who passed by while the
cocoon-building was in progress.)  I took the short video
above so you can get a better idea of what it looks like when a
silkworm is partially through the cocoon-spinning process.

Final thoughts

“My initial reaction is that is a
fair amount of work to do for 100 chicken feeder worms,”
one of our readers commented on a previous post.  On the
one hand, I think he’s right — I definitely put more work into
our silkworms than the output merited.  I figure it took
about five to ten minutes a day to care for our 300 silkworms, and
even if every one had survived, that wouldn’t have been a huge
amount of chicken feed for my 4.3 hour effort.

On the other hand, I think silkworm culture has potential if we
streamline the operation and have more mulberries close at
hand.  (Also, if you have kids or other free or cheap labor,
silkworms look much better.)  Mark will be putting on his
inventing cap about ways to make silkworm culture easier during
our next iteration of the experiment, so stay tuned.