Cold to preserve specimens.

Ron Gatrelle gatrelle at
Wed Oct 11 13:03:50 EDT 2000

    The subject here is the long term preservation of adult specimens via
refrigeration. This is presented as general information to everyone.
    In the discussion between Linda Rogers and Yo, we considered the
possibility of preserving living adult butterflies via subjection to cold. I
say this works. She says it does not. Well, I have often employed this
method to keep specimens alive for weeks. I learned this technique many
decades ago from some of the "old" collectors who collected adult females,
then kept them alive until suitable host plants were located to present to
the females for them to oviposit on.
    Specimens collected in the field are placed in "loose" envelopes to
prevent pressure on the specimen but tight enough to prevent "flapping."
These specimens are placed in portable coolers (with ice) to prevent
dehydration. Once back to base the specimens are placed in a regular
refrigerator set on low cool. This slows down the metabolism of the
specimens. A very small amount of water is placed inside the plastic
container containing the specimen envelopes. They do not get wet, but they
stay hydrated. (Do not lay the envelope on its side, keep specimen upright.)
Each specimens is taken out of the refrigerator every day, slowly warmed up,
and fed. I feed them with room temperature grape or apple juice, or sugar
water. If sugar water is used it must be powdered sugar not granular sugar.
Granular sugar will crystallize in their feeding tubes and they will die.
This is a tedious process and must be carried out carefully so as not to
"hurt" the specimens -- no damage to legs or antennae.
    I have kept specimens alive by this method for about three weeks. I
heard of one guy, about 20 years ago, you kept some tropical foreign stuff
alive for a few months. Don't remember who though, or what species. They
were mailed to him in a big package with some kind of cooling agent in it.
It would be interesting to see how long specimens could be preserved and by
what other adjustments to this process. We know that in nature this is how
adults overwinter. The northern overwintering species have a kind of
anti-freeze in their circulatory system. So they survive in sub zero
    Once the proper host is available, I feed the specimens and place them
in screened containers containing fresh cut new growth of the host outside
in partial sun. They need to be quite warm but not hot or they will die.
Once they have laid their eggs I release the females back into their natural
settings. (I usually only need to keep a specimen about 5 or 6 days.)
    This is something collectors and watchers can both do as we all enjoy
rearing stuff and watching their development. It also keep collectors from
catching "hoards" of wild specimens -- they take one female and get 10 to
200 specimens. Watchers only, can use the reared specimens to repopulate
areas or reinforce dwindling populations. Government and groups sometimes do
this but at great expense -- and with very very few species. When regular
people do it a whole lot more species are given a shot-in-the arm and for
    Now, the next discussion will be on. "OH NO! Don't introduce specimens
it's a bad idea. It promotes disease, predation, and upsets the natural
balance." it is true that a species SHOULD NEVER BE RELEASED AT A SITE WHERE
most of the people who say this should not be done at all are associated
with the groups (themselves) who would get paid to do this. Which tells me
that the real objection is not population reinforcement or reintroduction.
It is about who does it.  If we enthusiasts do it for free, they don't get
paid. I've been on both sides of this coin -- paid (by government) and non
Ron Gatrelle

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