In my
last post, I wrote
that I wasn’t sure how many silkworms you could raise on a single
mulberry tree, and that got me wondering whether chickens fed silkworms
would use land more or less efficiently than those fed corn and
soybeans.  I don’t expect to be feeding our flock solely on
silkworms any time soon, but it’s an interesting thought-problem when
trying to decide how much space to commit to mulberries.



The hardest part of my
calculation was guessing how many silkworms a hen would have to eat in
a day if they provided her sole ration.  I couldn’t find any data
on nutritional value of silkworms at the two-inch stage, so I used
information for the less palatable pupae, which clock in at 2,881
calories per dry pound.  Using a lot of rough figures, I came up
with a chicken needing 33 two-inch silkworms per day, or about 12,045
per year.  (Silkworms would really only be grown during the
summer, but presumably you could freeze or dry them for the winter.)



If you’re raising mulberries
to be fed to silkworms, you don’t generally let the plants turn into
trees.  Instead, you space the plants two feet apart in all
directions and coppice
repeatedly, getting perhaps 16 tons of fresh leaves per acre, which
might be enough to feed 640,000 silkworms per acre per year. 
Another figure is less optimistic and suggests you may only get 160,000
silkworms per acre per year.



Depending on which
figure you use, you could raise 13 to 53 chickens on the silkworms from
one acre of mulberries processed by silkworms.  In contrast, Gene
Logsdon suggests you can keep one chicken going for a year on a bushel
of grain, and you
can grow about 40 bushels of wheat on an acre.  So it’s conceivable
that silkworms could be comparable to grain…if you don’t mind the
work of hauling mulberry leaves to your insects two or three times a
day.



Of course, this is just a
thought problem.  On a diversified homestead, it makes sense to
coppice the mulberries more lightly so the bushes provide fruits as
well as silkworms, in which case you should expect to get enough leaves
for only about 15 to 30 silkworms from each bush.  (A mature tree,
on the other hand, is reported to feed about 100 silkworms.) 
Clearly, I’ll be a bit hard-pressed to come up with enough leaves to
feed the offspring of my 200 silkworm eggs this year since I’ve only
got one hefty and two puny mulberry trees in the ground so far. 
So, I let Mark talk me into adding two new varieties to our collection:

• Oscar’s Mulberry (Morus alba)
  — Edible in the red stage when they have a raspberry-like flavor, or
  in the black stage when they are among the finest flavored of hardy
  mulberries.  Very early ripening.  Zone 5-9.
• Silk Hope Mulberry (Morus alba
  x M. rubra) — Similar to
  Illinois Everbearing, but superior in size and flavor.  Excellent
  quality with a long fruiting season.  Widely adapted, tolerates
  drought or high humidity.  North Carolina selection by A. J.
  Bullard.  Zone 5-9.

If silkworms turn out to
be as good a fit for our homestead as I’m hoping, we should be able to
ramp up production dramatically in a year or two.  Thanks for
bearing with my flights of fancy in the meantime!