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Index of Subjects --Apple-Mail-241-481734968 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed Hi Steve, Although my knowledge of insect physiology is minimal I can make a =20 couple of comments: 1) Decomposition produces heat and the environment where these flies =20 live - large heaps of decomposing seaweed - may stay warmer than the =20 local ambient temperature thanks to their internal heat-generating =20 capacity. This may allow these flies to stay relatively active year-=20 round. 2) In my work on sub-cortical beetles I've found a suite of insects =20 that remain active all winter. The environment under bark is rather =20 sheltered and when the sun comes out in the winter, dark bark quickly =20= absorbs sunlight and the space under the bark warms up. If you peel =20 back the bark of trees in the early stages of decomposition (i.e. =20 when cambium feeders are still active and the bark has not yet begun =20 to physically crack open and break-down) on a sunny day, the beetles =20 that are found there (bark beetles, aleocharine rove beetles, and =20 others) are often quite active. Of course when the sun disappears and =20= the temperature goes down, they rapidly slow down. ;-> Although I've never investigated the physiology of beetles in this =20 micro-environment, I would think they would have to have really =20 effective anti-freeze mechanisms in order to to make these relatively =20= fast physiological adjustments on a daily basis. In general I think that small, dark-coloured entities like many =20 insects can be very adept at absorbing sunlight and thus raising =20 their body temperature above the ambient. Snow-fleas (Collembola) =20 certainly thrive in these circumstances. All the best! Chris On 20-Feb-07, at 11:32 PM, Stephen Shaw wrote: > Hi Murray, > That's an intriguing observation. Roughly what temperature would =20 > it have been > when you saw this, below zero? I'm interested generally in flies =20 > and didn't > realize that any adults of such groups were around at these =20 > temperatures, or at > all in February. As a sort of reference point, I recall reading =20 > that the UK > low-temperature record for an insect "behaving" was -5=B0C for a =20 > bristletail > (wingless insect) that someone observed sitting on a seaside rock =20 > in Wales, > whereupon it promptly ran away. I found that it takes a -7=B0C = surface > temperature (aluminium)to immobilize the same species that we also =20 > get here > (they hibernate over winter here in sea cliff crevices). Flies like =20= > other > insects are cold-blooded, and many cell systems like important =20 > enzymes have > temperature optima and slow down and eventually shut off when the =20 > temperature > drops, so the animals then can't perform at all, e.g. fly around. > > I think that 'kelp flies' is a name usually restricted to the =20 > family Coelopidae, > with only a few species here in the genus Coelopa. The Manual of =20 > Nearctic > Diptera doesn't mention anything about year-round adults or low =20 > temperature > behaviour, though that's not the main thrust of MND so perhaps this =20= > doesn't > mean much. > > Maybe all this is well-known locally here -- has anyone else seen =20 > these flies > flying around recently, for instance while birding around the high =20 > tide line? They tend to fly in small low clouds around piles of =20 > seaweed washed up there, > in summer. If anyone has info and has an idea of what the =20 > temperature was at > the time, it would be interesting to hear about it. Do birders =20 > ever set out > armed with digital thermometers, now quite inexpensive? > Steve, Halifax > **************************** > > Quoting dowitcher <dowitcher@eastlink.ca>: >> on sunday at clam point i had kelp flys flying around in among all =20= >> this snow. >> >> Murray R Newell >> Cape Sable Island >> Nova Scotia _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._.=20= _. Christopher Majka - Nova Scotia Museum of Natural History 1747 Summer Street, Halifax, Nova Scotia, Canada B3H 3A6 (902) 424-6435 Email <c.majka@ns.sympatico.ca> _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._.=20= _. --Apple-Mail-241-481734968 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 <HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; = -khtml-line-break: after-white-space; ">Hi Steve,<DIV><BR = class=3D"khtml-block-placeholder"></DIV><DIV>Although my=A0knowledge of = insect physiology is minimal I can make a couple of = comments:</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><DIV>1) = Decomposition produces heat and the environment where these flies live - = large heaps of decomposing seaweed - may stay warmer than the local = ambient temperature thanks to their internal heat-generating capacity. = This may allow these flies to stay relatively active = year-round.</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><DIV>2) = In my work on sub-cortical beetles I've found a suite of insects that = remain active all winter. The environment under bark is rather sheltered = and when the sun comes out in the winter, dark bark quickly absorbs = sunlight and the space under the bark warms up. If you peel back the = bark of trees in the early stages of decomposition (i.e. when cambium = feeders are still active and the bark has not yet begun to physically = crack open and break-down) on a sunny day, the beetles that are found = there (bark beetles, aleocharine rove beetles, and others) are often = quite active. Of course when the sun disappears and the temperature goes = down, they rapidly slow down. ;-></DIV><DIV><BR = class=3D"khtml-block-placeholder"></DIV><DIV>Although I've never = investigated the physiology of beetles in this micro-environment, I = would think they would have to have really effective anti-freeze = mechanisms in order to to make these relatively fast physiological = adjustments on a daily basis.</DIV><DIV><BR = class=3D"khtml-block-placeholder"></DIV><DIV>In general I think that = small, dark-coloured entities like many insects can be very adept at = absorbing sunlight and thus raising their body temperature above the = ambient. Snow-fleas (Collembola) certainly thrive in these = circumstances.</DIV><DIV><BR = class=3D"khtml-block-placeholder"></DIV><DIV>All the best!</DIV><DIV><BR = class=3D"khtml-block-placeholder"></DIV><DIV>Chris</DIV><DIV><BR><DIV><DIV= >On 20-Feb-07, at 11:32 PM, Stephen Shaw wrote:</DIV&