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<font face="Helvetica, Arial, sans-serif">Hi Frank,<br>
<br>
I cannot imagine why these larvae should have any problems with a
"little bit" of winter. <br>
Larvae can be found very deep in rotholes (see Rotheray's monography),
and still have no problems getting to enough oxygen to survive. Also,
there is almost no better insulation in nature, than wood. And because
there is always enough air between the vessels of wood, there should be
little problems for larvae to find oxygen there.<br>
Many saprophagus Syrphidae live in countries and areas with much
harsher winters than we experience here! <br>
Also one can imagine that, in times when it is very cold, just the
larvae's activities will be lowered down. In those times they need less
oxygen as well, I would say. <br>
<br>
It is very good that you want to go out looking for larvae (found
Sphegina larvae myself only two days ago in the Netherlands). But focus
on the living. And IF you would find dead ones (be sure they are dead
when you find them), it's a "bonus" on the job. But dead larvae decay
rather fast... <br>
<br>
Greetings, André<br>
<br>
<br>
<br>
<br>
</font><br>
Frank Van de Meutter schreef:
<blockquote cite="mid:4B71310D.1020200@Bio.kuleuven.be" type="cite">Hi
all,
<br>
<br>
I planned this winter to start a search for some rare water filled
treehole/treecavities inhabiting syrphids in Belgium. Winter is however
particularly harsh here (and over much of Europe), and all these small
water bodies that I visited are frozen for more than six weeks now. It
appears to me that the whole of the water content in the tree rotholes
and cavities is now frozen. This makes me question whether syrphid
larvae will be able to survive these conditions? Even if not all is
frozen, they should experience oxygen shortage? Comparably, in ponds
and pools, it is known that severe frost may also wipe out a
considerable fraction of the aquatic community (though I know nothing
on syrphids living there). When the water starts to melt I will see
whether many dead larvae can be found. Right now, I would like to ask
whether anyone has some previous experience/knowledge on this?
<br>
<br>
<br>
beste wishes,
<br>
<br>
Frank
<br>
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