Hoverfly checks please

[MattPrince]

Think I've got these down to rights, but confirmation and constructive comment always welcome

First two are (i think) Myathorpa Florea, I was a bit surprised to see how strong the bars are in comparison to the illustration in Stubbs.

Final one is Eristalis - Horticola? Going on wing venation, overall shape and patterning and the wing shades?

All at Dawlish Warren 7th August 2010.

Thanks for Looking.

[Jason Green]

Afternoon Matt,

Yes, I agree (though will see what others also think of the second, but it looks good!)

Take care,

Jason

[Chas]

I have had both of these species in my Exeter garden last year. (Just for information).

[JRsbugs]

It's not enough to go on the wings alone, somehow I don't think it's Eristalis horticola just because it has orangey segment joints, and some dark sinuosity in the wings.

You really need to see other features to say it's E. horticola.

1) In the males the front femora have long yellow hairs
2) The hind femora are orange at the base.
3) The pterostigma should be a little longer than the one in question

From what I can see, I would think it's E. interrupta, because:

1) The hind femora looks black with yellow at the apex
2) The pterostigma looks small and squarish
3) It looks to have a plumose face but that's not visible enough to say

Ideally I would like to see a full view of the face and a hind femur.

The only real feature I could separate out from those is the small squarish pterostigma, all else is speculation. I'm not convinced fully without seeing more, not even about the pterostigma.

Janet

[MattPrince]

Thanks for the input everyone - especially Janet.

Bit confused as Stubbs doesn't have E. Interupptus - quick surf indicates this is what Stubbs called E. Nemorum.

I'll see if I got anything else on the camera for this one - but I think I concentrated on the 'nice' one and skimped on the Eristalis..

[Geoff F]

Which version of Stubbs are you using Matt? 2002 edition, page 444 illustration 7, E. interruptus.

I fully agree with Janet's comments about the need to see more details here. As she says, the small crisply outlined stigma doesn't go beyond the join of vein Sc and the wing edge. Which does suggest E. interruptus.

The abdomen colouration is quite similar to a typical E. horticola but this family is notoriously variable in abdomen colouration. The typical E. interruptus which I have in my garden have very little yellow on their abdomen and appear more like E. tenax.

The same variation applies to Myathropa florea.

[MattPrince]

Sorry about the appauling delay in replying Geoff - a few login problems !

I was using the 2nd Edition of Stubbs with the supplement, which didn't help, though to be honest it still included interupptus - albeit under the name nemorum - so with a bit of patience and luck this should still have keyed out properly (at least in the field if not by the photographs)

Post bird fair I've got the latest version (and am now dead keen to get hold of the B&M distribution maps). I spent yesterday in Ashclyst forest getting to grips with a few new ones (rhingia campestris was nice), missed out on a xylota sp., and keying out quite a few eristalis, syrphus, heliophilus (I'm not killing any of the beasties at the moment - but sticking them in small glass tubes and trying to use a hand lens / field microscope - can be extremely frustrating!). Interupptus came up several times as did horticola (smeared stigma, clear wing shades, leg markings keyed out OK).

Keyed out e. similis on accident though (inexperience with what counts as 'dusting') so its still early days

Final list :- episyrphus balteatus, syrphus vitripennis, rhingia campestris, heliophilus pendulus, eristalis horticola, eristalis tenax, eristalis interupptus. Not many considering the numbers that were about - but a start - pity its so late in the season!

[Roger Morris]

Hello Matt

A useful start but I think you will find retaining specimens will help in the long term. Most species are actually quite tricky and require microscopic identification.

The debate about your Eristalis is an example. Certainly this is not E. horticola. I'm not entirely convinced about En interruptus - I have a bagging feeling it is E. pertinax based on the shape of the abdomen - but the angle may be deceiving.

Regards

Roger

[MattPrince]

Hello Roger,

I am using a field microscope - little more than a toy in many respects - its far from ideal and very frustrating getting the little devils in the correct area for viewing the relative feature of the key (still haven't seen the hairs on the upper surface of the squama for example) however it's x30 so with patience it is possible to get acceptable views of most of the features in the key. Interpretation can be difficult for someone of my inexperience though.

Regards,
Matt