Diptera.info :: Identification queries :: Diptera (adults)
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 Australian Tachinidae?
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| Graeme Cocks |
Posted on 29-08-2010 23:02
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 Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
I think this is Tachinidae. Is genera possible? Malaise trap. Townsville, Australia. Graeme Cocks attached the following image:  [87.07Kb] |
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| Kahis |
Posted on 29-08-2010 23:15
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 Member Location: Helsinki, Finland Posts: 1999 Joined: 02.09.04 |
I would rather think Muscidae or Anthomyidae.
Kahis |
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| Graeme Cocks |
Posted on 29-08-2010 23:26
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
Thanks Kahis. I thought the prominent subscutellum made it Tachinidae? |
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| ChrisR |
Posted on 30-08-2010 07:54
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 Super Administrator Location: Reading, England Posts: 7706 Joined: 12.07.04 |
I'd say it's an anthomyid - I see no subscutellum - just the part of the thorax that runs down to the abdomen  By the way Graham, are your photos being over-compressed when you save them? Because they appear very blocky with a massively reduced colour palette. Manager of the UK Species Inventory in the Angela Marmont Centre for UK Biodiversity at the Natural History Museum, London. |
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| Graeme Cocks |
Posted on 30-08-2010 08:25
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
Looks like I need to reapraise what I think is the subscutellum. That is the second time my pics have been commented on in this forum. Very curious. I use normal jpg compression and the picture in this thread looks OK to me. However there is obviously something wrong. Thanks for pointing it out. Not sure what I can do about it though. |
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| Graeme Cocks |
Posted on 30-08-2010 08:37
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
Chris, I have submitted some mosquito pics for the gallery. Could you have a look at them please and tell me what you see? It would be embarasing if they also appear to be of poor quality. I have pride in the quality of my pictures. |
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| ChrisR |
Posted on 30-08-2010 08:44
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Super Administrator Location: Reading, England Posts: 7706 Joined: 12.07.04 |
As a general rule of thumb most tachinids (one or two don't obey the rule) have a curved median vein - this fly doesn't so it would be a very odd tachinid ... and the general shape looks more anthomyid-like. The posterior part of the thorax can confuse people because it seems to be a big lump under the scutellum, but a subscutellum will be a smaller, rounded bulge under the scutellum just a bit smaller in thickness than the scutellum itself. As for the photo quality, it's off - it immediately reminds me of the effect that you get when you save a photo as a 256-colour GIF file (ie. the 16-million colours get massively reduced and the image appears almost posterized with flat blocks of colour) ... but yours is obviously a JPEG so I can only think that the compression setting is set too aggressive - try having a look at the options you get at save time and aiming for a larger file but with better quality. On something like PhotoShop you can set the quality/compression level at about 90% (ie. loosing about 10% of quality) and it will reduce the file size quite a lot. Usually there is not need to go much below 80-90%.
Manager of the UK Species Inventory in the Angela Marmont Centre for UK Biodiversity at the Natural History Museum, London. |
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| ChrisR |
Posted on 30-08-2010 08:53
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Super Administrator Location: Reading, England Posts: 7706 Joined: 12.07.04 |
Just had a look at a few of the mosquito photos and they do seem to suffer from the same effect as the others - a blocky, flat colour palette ... the Mansonia shows it less though because there are less colours in the original anyway ... I will let Paul decide if they are OK for the gallery. To me they just look like over-compressed JPEGs so I would double-check in your software what the compression is set to - and choose something at the other end of the scale, just in case you are misinterpreting what the value means. I know when I looked into my software here the ratio/% didn't seem logical ... 90% compression sounds like you are going to loose a lot of quality but actually it meant the reverse. PS: if you like you are welcome to send me an original photo (uncompressed) and I will have a go with it here - just in case there is some effect being caused in the camera
Edited by ChrisR on 30-08-2010 08:55 Manager of the UK Species Inventory in the Angela Marmont Centre for UK Biodiversity at the Natural History Museum, London. |
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| Graeme Cocks |
Posted on 30-08-2010 08:58
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
I think I have been in error with the subscutellum. I was just looking for a bulging lobe below the scutellum and nothing more. Thanks. |
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| Graeme Cocks |
Posted on 30-08-2010 09:08
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
There are no adjustments available to me for jpg. All my pics are scans from a flatbed scanner so that's fair enough re the lack of settings. If you don't mind helping me to get better pics from it that would be great. What I have available is just different file types. Maybe I need to use raw as a starter and adjust file size later. |
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| ChrisR |
Posted on 30-08-2010 09:18
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Super Administrator Location: Reading, England Posts: 7706 Joined: 12.07.04 |
Interesting, it might not be compression that is the problem - perhaps it's simply the DPI or scanning resolution that's creating the speckled effect? Are you just scanning the specimens on a flat-bed scanner? Perhaps it needs to be set the highest possible scanning resolution to be able to make sense of such small subjects?
Manager of the UK Species Inventory in the Angela Marmont Centre for UK Biodiversity at the Natural History Museum, London. |
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| Graeme Cocks |
Posted on 30-08-2010 09:35
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
This is really curious. I wish I could see what you see. I don't see a speckled affect. I use the highest settings. The scanner has twin heads which gives better depth of field than other scanners. Dunno what is going on. |
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| Graeme Cocks |
Posted on 30-08-2010 22:49
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
Chris, I've sought 2nd, 3rd and 4th opinions on this picture and all say there is nothing wrong with it. |
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| jorgemotalmeida |
Posted on 31-08-2010 00:45
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 Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
Also I see the same as described by Chris. Speckled effect in all photos.  |
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| Graeme Cocks |
Posted on 31-08-2010 00:59
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
Thanks for the response. I believe we are seeing different views, here and at diptera.info. But why? It has me puzzled. The picture is high resolution 2400x2400 dpi, and yet you appear to be seeing a low resolution version. |
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| Graeme Cocks |
Posted on 31-08-2010 01:03
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
There is an earlier picture of mine in the gallery, in Nycteriidae. Would you have a look at it please? |
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| jorgemotalmeida |
Posted on 31-08-2010 01:23
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Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
Dear Graeme, The photo of your Nycteribiidae fly has 70 kB and it has the same problem: too much speckled and it seems like a very low resolution image. Try to save the photos with 185 kB (but I think this will not resolve the problem.. but give a try). Which photo editor do you use? |
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| Graeme Cocks |
Posted on 31-08-2010 01:33
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
That Nycteribiidae has been used in a publication which should make it adequate quality. It is 2400x2400 dpi which in my opinion is high resolution. Going any higher does not really improve the quality. I don't use a photo editor. |
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| Graeme Cocks |
Posted on 31-08-2010 01:39
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Member Location: Townsville, Australia Posts: 3083 Joined: 09.09.08 |
Could you have a look at the pics on my website "The Insects of Townsville". I started it in 2004 and it has never had a comment re the lack quality of pictures. |
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| jorgemotalmeida |
Posted on 31-08-2010 01:55
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Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
it's the same. I see many speckled photos. Try to send some photos to me - original photos. I will upload them to here tomorrow. |
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