The first insect to be seen this year of any size!

[ultramarine]

I must apologise for the quality of this photograph but can anyone identify this for me. Basking on a stone in the first bit of wintry sunshine this year it looks like a hoverfly but I didn't see it hovering.

[aeshna5]

It's one of the drone-flies ( a type of hoverfly); I think Eristalis tenax.

[Geoff F]

E. tenax is quite possible at this time of the year; I saw a couple last week.

But there are several similar species so it is impossible to be absolutely certain.

Incidentally, quite a lot of hoverflies don't spend that much time actually hovering, while there are a few flies which also regularly hover.

I find that the best initial clue is to look at the wing veins near the wing tip. Hoverflies should have a cross vein running from the front wing edge to back edge near the wing tip, very approximately speaking. It is actually two veins with a longitudinal vein between them but with some species it can initially look like one vein.

[ultramarine]

Thank you! I try to identify insects using the Collins Guide ( pub. 1986 by Michael Chinery ) I can find most stuff but it obviously has its limits...and my skills aren't brilliant. Its good to try to find your ID in the book because it embeds it in my memory then. Or at least, thats the theory! I take it there are lots of different drone flies? The one in my book doesn't look so dark and is more golden-striped. Thanks for the tip about the veining. Do you need a microscope for that sort of detail or will a hand held lens do ? How do you do this identification? I dont want to kill anything!
Cheers U.

[Jason Green]

Evening UM,

Glad to see these about again! I'm as yet to have the pleasure this year, but haven't had many opportunities in the last few weeks either. Let's see if I can suggest anything here.

Originally Posted by ultramarine

I take it there are lots of different drone flies? The one in my book doesn't look so dark and is more golden-striped.

We have about 270 hoverflies in the UK, I believe the Drone ones are Eristalis tenax and E. pertinax.

Your description of the one in Chinery sounds a touch like Helophilus pendulus.

Originally Posted by ultramarine

Do you need a microscope for that sort of detail or will a hand held lens do ? How do you do this identification? I dont want to kill anything!

A hand-lens would do for these. These are differenciated in the field by the eyes; pertinax having uniformly-haired eyes, whilst those of tenax will show a partitioning of the hairs just beyond the mid-line from left to right across the eyes. This is actually quite an obvious feature, and makes them appear either two-shaded or more 'textured' than you'd expect in reality.

Yours is as suggested, very likely tenax. Although you can't see the hairs, there is an apparent difference in the colour of the eyes - sort of bluey-green for the left eye and just red for the other. I suppose this is how the light caught the hairs in the photo or something, not sure!

Take care,

Jason

[Geoff F]

And today, I saw my third E. tenax female for the year.

Jason's point about the eye colour banding is correct but often, when the light is 'wrong', this can be difficult to see.

A more reliable first clue for this species is to look for an all dark hind leg, but there are other slight differences as well.

With practice, it is possible, in good light, (and with excellent close up eyesight) to see the wing veins of these larger hoverflies without magnification. All Eristalis species have a clearly defined deep loop in one of the longitudinal wing veins. Check out a few samples in the Gallery and it will soon become obvious.

[yukonite]

25/02/2011 midge hatch

[ultramarine]

Thanx to Geoff and Jason, I have printed off this information and will definitely hone my identification skills this summer !