Martha V. Lutz & Charles T. Lutz
lutzrun at avalon.net
Mon Sep 11 16:53:21 EDT 2000
Becky Droster wrote:
" I have a couple of remaining questions
though. I live in Wisconsin where the winters can be very cold. It is
not at all uncommon to have stretches of a week or more (sometimes
considerably more) in which the temperature will stay well below
freezing. Surely the pupae out in the wild must freeze during such
weather. Why should they not be frozen in captivity? I am also
uncertain about when I should start to refrigerate. The weather here
has been quite warm and remains in the eighties now. It could be
anywhere from a couple of weeks to more than a month before the first
frost. Should I put it in cold storage immediately or try to time it
with the cooler weather of fall?"
I live in Iowa, and have routinely kept H. cecropia pupae in our home
freezer during the winter. However, I usually bring them down to that
temperature gradually. I keep them at room temperature until mid-September
or early October, then give them a month or so in the refrigerator, then
put them into the freezer for 2-3 months. They can also simply be kept in
a vermin-proof (!!!) cage, placed where it will not flood, and left
outdoors or in an unheated garage. As a univoltine (one generation per
season) species the cecropia pretty much always enters diapause as a pupa,
and will break diapause and begin development when warm temperatures return
in the spring.
I usually bring my pupae up to room temperature in March. It can be done
earlier, although the time to emergence is less predicatable than in
species such as Actia luna. H. cecropia has at least two broad emergance
peaks in most areas, which some specialists believe is a way of 'spreading
the risk' of hatching either too soon or too late. Hatching early gives an
advantage in terms of getting into the local habitat first, but runs the
risk of a late freeze, greater apparency to predators (this refers to
larvae, feeding while leaves are small), or failure to find a mate (the
adults). Adult Saturniids have no functional mouths and do not feed. If
you want it to live for a while, keep the moth in a (clean, empty!)
margarine tub in your refrigerator at night.
For classroom use, you want this one to emerge earlier than some of the
local wild ones (I'm guessing early June at the earliest in Wisconsin).
Your best bet is to gradually lower the temperature (put it in
air-conditioning, or a cool basement for a few weeks), then refrigerate it
in October. Freeze it mid-November through January, and bring it to room
temperature around Valentine's Day. It should hatch by the end of March.
Shift these dates later by 2-4 weeks if you would rather have it emerge in
mid- to late April or early May.
Where it is hot, humid, and horrible . . . but our last Monarch chrysalis
hatched on our dining room table this morning, and will be on its way to
High School tomorrow--along with it sibs, who will all be tagged and
released by the AP biology class!
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