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Stephen Shaw wrote:
> Regarding the comments
> about the thermally protected micro-environment in the air spaces
> under stuff
> like washed-up seaweed, fully agreed, but not in the case of the
> adults if they
> come out and cavort on the snow where their bodies will rapidly
> equilibrate to
> ambient temperatures (probably in seconds). So could it be that these
> are
> simply occasional doomed escapees
Hi Steve & All, Feb 23, 2007
In the case of insects with legs sufficiently long to keep the body
well above snow level, I would expect on calm sunny days significant
warming by reflection of sunlight from snow.
That being said, the massive reproductive potential of the typical
insect shows that most individuals must come to grief before reaching
reproductive age and getting stranded on a snowbank in brisk weather is
no doubt one way to do so. At the very least they would be a sitting
duck for any insectivore that came along.
From about now on, when stumps of recently cut hardwoods start to
bleed on sunny days, one will usually see flies of several stripes, that
presumably overwinter as adults in some nearby cold corner, feeding on
the sap.
Some flies are relatively tolerant of cold. In December, 2001 I
found some crane fly larvae in debris on polyethylene that was on top of
a woodlot woodpile and brought some home to a woodpile in the yard where
they spent the winter well above the protection of warm snow or warm
soil. They wintered well and adults emerged sometime after June 5.
In a related vein, I wonder if the sometimes profuse complement of
bristles, hair or wool may reduce heat loss during flight or while
landed in windy weather, by decreasing air flow near body parts.
Yours truly, Dave Webster, Kentville
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