[NatureNS] Hover Fly

Date: Mon, 25 Sep 2006 23:21:21 -0300
To: naturens@chebucto.ns.ca
From: Angus MacLean <angusmcl@ns.sympatico.ca>
References: <6.2.1.2.0.20060923203131.01e330f0@pop1.ns.sympatico.ca>
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Thanks, Chris. Perfect match for the abdomen but as you state, this
doesn't always have to be exact. The &quot;frons&quot; does not match
with the fly in my photo, obviously another feature that variable.<br>
Angus<br><br>
At 07:28 PM 9/25/2006, you wrote:<br>
<blockquote type=cite class=cite cite="">Hi Angus,<br><br>
On 23-Sep-06, at 8:39 PM, Angus MacLean wrote:<br><br>
<blockquote type=cite class=cite cite="">Here's another Hover Fly with a
beautifully marked abdomen. <br><br>
<a href="http://www.flickr.com/photos/58321572@N00/250842872/" eudora="autourl">
http://www.flickr.com/photos/58321572@N00/250842872/</a></blockquote><br>
<blockquote type=cite class=cite cite=""><br>
Another Hover Fly I uploaded earlier was thought to be a <i>Eristalis</i>
spp. but this one although somewhat similar, I believe is a
<i>Metasyrphus</i> spp., perhaps americanus although the latter has
brighter yellow striping on the abdomen. </blockquote><br>
This is a very distinctive species -- <i>Meliscaeva cinctella</i>
(Zetterstedt, 1843), a monospecific genus. It is a common and widespread
in both NS and NB. Some photos can be seen at:<br><br>
<a href="http://insektenfotos.de/Meliscaeva%20cinctella%20(Spaete%20Fruehlingsschwebfliege)_002.jpg">
http://insektenfotos.de/Meliscaeva%20cinctella%20(Spaete%20Fruehlingsschwebfliege)_002.jpg</a>
<br>
<a href="http://bugguide.net/node/view/21554/bgimage" eudora="autourl">
http://bugguide.net/node/view/21554/bgimage</a><br><br>
<i>Metasyrphus</i> are much wider and heavier bodied flies and the
abdominal black bands of <i>M. americanus</i> (at least in most of the
individuals that I have examined) have medial lobes.<br><br>
<blockquote type=cite class=cite cite="">The <i>Eristalis </i>spp. can be
found at:<br><br>
<a href="http://www.flickr.com/photos/58321572@N00/228628774/" eudora="autourl">
http://www.flickr.com/photos/58321572@N00/228628774/</a><br><br>
Comments are appreciated.</blockquote><br>
This is doubtless <i>Eristalis tenax</i> (Linnaeus, 1758), a very common
and variable species in Nova Scotia.<br><br>
A note to those interested in insects: in general identifying insects
differs substantially from the process of identifying birds wherein one
tries to match the colour and pattern of &quot;field marks&quot; with
illustrations in books, etc. In some species of insects colour patterns
can be quite variable within a species and over the life-span of the
insect (i.e. many beetles begin adult life as very pale-coloured
&quot;tenereal&quot; individuals) or there are multiple species which
have overlapping or indistinguishable colouration and pattern. Much of
insect identification is based on anatomical structure, features, and
proportions such as that of the mandibular and labial palps, antennal
segments; segments or proportions of tibia, tarsi, or femurs; venation of
wings; setation or punctation patterns on different parts of the body,
etc. <br><br>
What all this means is that coloration and pattern of insects can be a
rather unreliable and/or insufficient basis of identification.<br><br>
Cheers,<br><br>
Chris<br><br>
<font face="Times, Times">
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Christopher Majka - Nova Scotia Museum of Natural History<br>
1747 Summer Street, Halifax, Nova Scotia, Canada&nbsp; B3H 3A6<br>
(902) 424-6435&nbsp;&nbsp; Email
&lt;c.majka@ns.sympatico.ca
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