caterpillar cremaster

[John Lane]

Gerald Mines wrote"
"When the larval skin is nearly shed, the pupa "steps out" of the skin which
is still attached to the pupa by a ligament at the posterior end of the
pupa."
Then Sally got an email invoking "anal claspers".

Not to be overly "crochety", but . . .
posterior pupal ligament??

Scudder illustrated (using the Monarch) how butterflies with pendant pupae
"hang on" at pupation.  Perhaps someone with access to a good library and
more computer skills than I can scan this illustration and post it for all to
see.

In words:
In the moments between when the abdomen is withdrawn from the last larval
skin and before reattaching the to the silk button, the old larval skin --
with its crochets, (hooks on the anal prolegs) still stuck in the silk -- is
grasped/pinched between two abdominal segments by a lateral curling of the
abdomen.  While "hanging on" to the old larval skin by this abdominal
"pinch", the abdominal tip is withdrawn from the old larval skin and then
gyrated back into the silk button to engage the cremaster (with hooks like
the prolegs) into the silk.

John Lane, Grass Valley, Ca., usa

Gerald Mines wrote:

> Hi Sally,
>
> The caterpillar uses the anal prolegs (rearmost set of false legs),
> which have microscopic hooks, to clasp onto the silk pad.  When the
> larval skin is nearly shed, the pupa "steps out" of the skin, which is
> still attached to the pupa by a ligament at the posterior end of the
> pupa, and attaches it's cremaster to the silk pad.  The writhing motions
> of the pupa then cause the ligament to break and the larval skin falls
> away from the pupa.
>
> Gerald Mines
> Omaha, Nebraska
> http://www.tconl.com/~mines
>
> Sunsol Daniels wrote:
> >
> > My book says that pupae have cremasters to hook into the silk button.
> > How about the caterpillar?  How does it attach to the silk button before
> > it molts? Does it have a cremaster too?
> >
> > Sally