Subject: Re: Chrysalis- Dead or Alive?

From: James Kruse <[email-masked]>
Date: Thu, 9 May 1996 13:34:27 CST

Thu, 9 May 1996  Eric Jensen <[email-masked]>
0
> What is the actual status of the pupa/butterfly while in the chrysalis state?
>
> I have  an American Swallowtail that has been in chrysalis for over 6 weeks.
>  Yesterday, while watering, the chrysalis got wet and began to twitch.
> Otherwise, this chrysalis has never moved on its own.
>
> On the other hand, I have several Gulf Fritillary chrysalises that when
> touched, bend away from the stimulus.
>
> Does the caterpillar actually live on inside the chrysalis for a period of
> time? Or perhaps, does the caterpillar die immediately and the butterfly is
> now the living organism?
>
> Thank you for your assistance.
> Eric J
> [email-masked]
>

Hello,
        Interesting.  Actually the caterpillar, chrysalis/pupa, and
adult are all the same organism but in different life stages.   The
caterpillar is the "eating stage".  A caterpillar is essentially a
sack stuffing itself full of food to grow.  The pupa or chrysalis, is
sometimes called the "resting stage", a title which is quite false.
Though the pupa is often the diapausing stage, huge changes in
hormones and other chemical activity are changing the caterpillar
into a very different -structure and function- adult.  The molt of
the larval exoskeleton to the pupal stage is the last molt of the
immature insect.  The next molt will be the adult coming out of the
exoskeleton of the pupa.  This is the same animal.

    The pupa is often capable of a few limited movements.  The
twisting of the abdomen is response to some stimulus.  Your gulf
fritillaries to your finger, the swallowtail to the water hitting it.
Movements may be a feeble attemt to discourage a parasitoid, better
yet knock the parasitoid off and make it find you all over again, if
it can...  Most lepidoptera are in some sort of shelter, like a
cocoon or plant material, even the ground.

    This brings me to a question.  With Sphingids or Saturniids which
the larvae pupates under ground...  How does the pupa, about to molt
to adult, with the exoskeleton thinned and soft get out of the
hard field soil and sod layer?  When you are rearing them in peat moss
and potting soil its not a big deal.  This was a question when I was
a kid and I still have yet to hear the explaination.  Surely the
adult doesn't do it, no digging apparatus.  The pupae of which I
speak have the gin-traps on the sides and spike on the tip of the
abdomen...  I have noticed that the pupae I unearth before spring
seem to know that they are out of the ground, as they burst from
their pupae without so much as a twitch of the abdomen.

Thoughts, sources welcome!
Jim

Dept Entomology
Univ Wisconsin
345 Russell Labs
1630 Linden Dr.
Madison, WI 53706
608-262-4755

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From: Ron Rutowski <[email-masked]>
Date: Thu, 9 May 1996 11:36:35 -0700

>Thank you for your assistance.

Eric:

There are several  points I would make about the pupal stage  in response to
your questions.   First, it is alive.   There is no mouth or anus but there
are respiratory openings, spiracles, through which gas exchange occurs.
Second, you should think of the pupa as a stage unto itself with its own
special features and abilities.   There is no caterpillar or butterfly
living or dying in the pupa  although there are things going on inside that
lead from the caterpillar stage to the adult butterfly.   This involves
disassembling parts of the caterpillar and reassembling the basic components
into a butterfly.   Third, many pupae are capable of flexing the body.  Some
lycaenid pupae even produce sound.   I do not know if pupae are typically
able to move this throughout the pupal stage.   Fourth, many leps spend long
periods such as winter in the pupal stage in a sort of dormant state.  The
level of activity inside the pupae can change dramatically from one time
period to the next.  Finally, there are others who know much more about
these things than I do and I hope you will hear from them as well.

Ronald L. Rutowski                              Phone:  602-965-4369
Professor and Associate Chair                           602-965-6241
Department of Zoology                   FAX:    602-965-2519
Arizona State University                        email:  [email-masked]
Tempe, AZ 85287-1501  USA

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From: "DANNY A. BRASS" <[email-masked]>
Date: Thu, 9 May 1996 16:15:18 -0700

>Some lycaenid pupae even produce sound.

Is this audible to the unaided human ear?  Any thoughts on possible function?

Danny A. Brass