Note from ScienceLine Coordinator
The following is a contribution from Barbara, a
reader of ScienceLine:
"The caterpillar does use some sticky silk to
mount their tail onto the location they want to
transform - a branch, a butterfly house, etc. But
they do not 'spin' a cocoon. The chrysalis is
already in place under their skin, which they then
split and wiggle from until it falls off.
My 9 year old children and I were curious how
our very large striped (future black swallowtail
butterfly) caterpillars suddenly less than hour or
so later managed to so quickly become encased in a
soft green chrysalis much smaller than their body
was an hour earlier, when the were very inactive
and not moving for hours after they silk mounted
their tails to the wall of the butterfly house.
We tried each time to catch them spinning it. We
couldn't, because there was no spinning - I
noticed the rumpled shed striped skins beneath on
the bottom of the butterfly house, like a
discarded t-shirt. Mystery solved.
The soft green chrysalis then hardens up and
turns brown. You may see the chrysalis pulse and
wiggle at times. The transformation takes about 3
weeks or so before the butterflies begin to
emerge. We still have several more not ready to
go into a chrysalis yet, so perhaps I will video
them doing this."
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