Hoverfly for ID

Toby · #1 (**permalink**) 06-12-2009, 10:40 PM

bit surprised to find this fellow still active at Burnham Beeches this afternoon:

Jason Green · #2 (**permalink**) 06-12-2009, 10:58 PM

Hi Toby,

I believe it's Melanostoma scalare - the halteres appear greenish and the yellow abdominal markings are sharply angled as opposed to being bolder blocks as in melinum.

Good to see these still active - it doesn't look in bad condition, either

I don't think they'd say no to a bit of sugar at this time of year. It would be a good photo opportunity!

Take care,

Jason

JRsbugs · #3 (**permalink**) 07-12-2009, 02:45 AM

I'm leaning towards Melanostoma mellinum but wouldn't like to say for sure without a view of the face. The halteres don't look as green as they should for M. scalare, and the shapes I have found can be a little variable.

Janet

who is up very late

Jason Green · #4 (**permalink**) 07-12-2009, 08:47 AM

I did wonder about the halteres, but put it down to light/season. Yes, the physical shapes may vary - can you show me a scalare with the bold blocks I was telling you about? I'd be interested to have my view challenged. In this case I just can't see how mellinum's blocks could become six identical brackets, though obviously appreciate you not having said you were certain it was the other

Diptera.info - Photo Albums: Melanostoma mellinum (male) (1)
Blocks - mellinum

Hoverfly Recording Scheme - Album
Bracets - scalare

So, for me personally it's scalare

Up late dealing with a backlog of summer IDs I take it?

squishy · #5 (**permalink**) 07-12-2009, 11:15 AM

it does look more like scalare to me

Geoff F · #6 (**permalink**) 07-12-2009, 06:59 PM

As Janet said, all the important parts are hidden in this photo; and that includes the first set of abdominal spots which should be larger in M. scalare.

However, the abdomen of M. scalare is longer than M. mellinum and because this photo shows a bent abdomen I think it is appearing to be shorter than it actually is. The typical female M. mellinum abdomen should be widest just after the first pair of spots then taper towards the rear; while M. scalare has a gradually widening abdomen all the way.

Neither Stubbs nor van Veen mention the halteres colour so I wonder how reliable this is for the chief means of identification.

Stubbs does say that M. scalare can be found later than M. mellinum (November compared with October).

So putting it all together, I would think M. scalare is the most likely; but Melanstoma sp. is the safest.

Toby · #7 (**permalink**) 08-12-2009, 07:10 PM

thanks for replies and technical input, don't suppose this view will be conclusive, probably need view directly above:

JRsbugs · #8 (**permalink**) 09-12-2009, 03:47 PM

Sorry for the late reply, I have had phone line connection problems but have had replacements so should now be OK!

Before anyone makes too many decisions based on time of year or the shapes, take a look at my pic of a female M. mellinum taken in November this year.

Diptera.info - Photo Albums: Melanostoma mellinum (female) (2)

Having seen the face yes I would say it is M. scalare, due to the extra dusting which can be seen on the white triangles between the eyes. That is the only safest method really of separating the females, as said there are variations and photos often don't show the colour of the halteres in true colours due to flash etc., but in general they are a deeper green colour. This could alter with age etc.

Also take a look at the pic of a female I posted on the Syrhpid thread, it has very broad shapes and I could not put a name to it at all without seeing the face.

Jason, the pic you linked to of M. mellinum is a male which is far different to a female!